Please refer to the errata for this document, which may include some normative corrections.
See also translations.
Copyright �2002 W3C� (MIT, INRIA, Keio), All Rights Reserved. W3C liability, trademark, document use and software licensing rules apply.
This is the specification of the Platform for Privacy Preferences (P3P). This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P applications.
This section describes the status of this document at the time of its publication. Other documents may supersede this document. The latest status of this document series is maintained at the W3C.
This is the W3C Recommendation of the the Platform for Privacy Preferences 1.0 (P3P1.0) Specification.
This document has been reviewed by W3C Members and other interested parties and has been endorsed by the Director as a W3C Recommendation. It is a stable document and may be used as reference material or cited as a normative reference from another document. W3C's role in making the Recommendation is to draw attention to the specification and to promote its widespread deployment. This enhances the functionality and interoperability of the Web.
This document has been produced by the P3P Specification Working Group as part of the Privacy Activity in the W3C Technology & Society Domain.
Patent disclosures relevant to this specification may be found on the P3P1.0 patent disclosure page, in conformance with W3C policy.
Please report errors in this document to<EMAIL_ADDRESS>(publicly archived).
The list of known errors in this specification is available at http://www.w3.org/2002/04/P3Pv1-errata.
The English version of this specification is the only normative version. Information about translations of this document (if any) is available at http://www.w3.org/2002/04/P3Pv1-translations.
A list of current public W3C Technical Reports can be found at http://www.w3.org/TR.
The Platform for Privacy Preferences Project (P3P) enables Web sites to express their privacy practices in a standard format that can be retrieved automatically and interpreted easily by user agents. P3P user agents will allow users to be informed of site practices (in both machine- and human-readable formats) and to automate decision-making based on these practices when appropriate. Thus users need not read the privacy policies at every site they visit.
Although P3P provides a technical mechanism for ensuring that users can be informed about privacy policies before they release personal information, it does not provide a technical mechanism for making sure sites act according to their policies. Products implementing this specification MAY provide some assistance in that regard, but that is up to specific implementations and outside the scope of this specification. However, P3P is complementary to laws and self-regulatory programs that can provide enforcement mechanisms. In addition, P3P does not include mechanisms for transferring data or for securing personal data in transit or storage. P3P may be built into tools designed to facilitate data transfer. These tools should include appropriate security safeguards.
The P3P1.0 specification defines the syntax and semantics of P3P privacy policies, and the mechanisms for associating policies with Web resources. P3P policies consist of statements made using the P3P vocabulary for expressing privacy practices. P3P policies also reference elements of the P3P base data schema -- a standard set of data elements that all P3P user agents should be aware of. The P3P specification includes a mechanism for defining new data elements and data sets, and a simple mechanism that allows for extensions to the P3P vocabulary.
P3P version 1.0 is a protocol designed to inform Web users of the data-collection practices of Web sites. It provides a way for a Web site to encode its data-collection and data-use practices in a machine-readable XML format known as a P3P policy. The P3P specification defines:
The goal of P3P version 1.0 is twofold. First, it allows Web sites to present their data-collection practices in a standardized, machine-readable, easy-to-locate manner. Second, it enables Web users to understand what data will be collected by sites they visit, how that data will be used, and what data/uses they may "opt-out" of or "opt-in" to.
As an introduction to P3P, let us consider one common scenario that makes use of P3P. Claudia has decided to check out a store called CatalogExample, located at http://www.catalog.example.com/. Let us assume that CatalogExample has placed P3P policies on all their pages, and that Claudia is using a Web browser with P3P built in.
Claudia types the address for CatalogExample into her Web browser. Her browser is able to automatically fetch the P3P policy for that page. The policy states that the only data the site collects on its home page is the data found in standard HTTP access logs. Now Claudia's Web browser checks this policy against the preferences Claudia has given it. Is this policy acceptable to her, or should she be notified? Let's assume that Claudia has told her browser that this is acceptable. In this case, the homepage is displayed normally, with no pop-up messages appearing. Perhaps her browser displays a small icon somewhere along the edge of its window to tell her that a privacy policy was given by the site, and that it matched her preferences.
Next, Claudia clicks on a link to the site's online catalog. The catalog section of the site has some more complex software behind it. This software uses cookies to implement a "shopping cart" feature. Since more information is being gathered in this section of the Web site, the Web server provides a separate P3P policy to cover this section of the site. Again, let's assume that this policy matches Claudia's preferences, so she gets no pop-up messages. Claudia continues and selects a few items she wishes to purchase. Then she proceeds to the checkout page.
The checkout page of CatalogExample requires some additional information: Claudia's name, address, credit card number, and telephone number. Another P3P policy is available that describes the data that is collected here and states that her data will be used only for completing the current transaction, her order.
Claudia's browser examines this P3P policy. Imagine that Claudia has told her browser that she wants to be warned whenever a site asks for her telephone number. In this case, the browser will pop up a message saying that this Web site is asking for her telephone number, and explaining the contents of the P3P statement. Claudia can then decide if this is acceptable to her. If it is acceptable, she can continue with her order; otherwise she can cancel the transaction.
Alternatively, Claudia could have told her browser that she wanted to be warned only if a site is asking for her telephone number and was going to give it to third parties and/or use it for uses other than completing the current transaction. In that case, she would have received no prompts from her browser at all, and she could proceed with completing her order.
Note that this scenario describes one hypothetical implementation of P3P. Other types of user interfaces are also possible.
P3P policies use an XML with namespaces (cf. [XML] and [XML-Name]) encoding of the P3P vocabulary to provide contact information for the legal entity making the representation of privacy practices in a policy, enumerate the types of data or data elements collected, and explain how the data will be used. In addition, policies identify the data recipients, and make a variety of other disclosures including information about dispute resolution, and the address of a site's human-readable privacy policy. P3P policies must cover all relevant data elements and practices. However, legal issues regarding law enforcement demands for information are not addressed by this specification. It is possible that a site that otherwise abides by its policy of not redistributing data to others may be required to do so by force of law. P3P declarations are positive, meaning that sites state what they do, rather than what they do not do. The P3P vocabulary is designed to be descriptive of a site's practices rather than simply an indicator of compliance with a particular law or code of conduct. However, user agents may be developed that can test whether a site's practices are compliant with a law or code.
P3P policies represent the practices of the site. Intermediaries such as telecommunication providers, Internet service providers, proxies and others may be privy to the exchange of data between a site and a user, but their practices may not be governed by the site's policies. In addition, note that each P3P policy is applied to specific Web resources (Web pages, images, cookies, etc.) listed in a policy reference file. By placing one or more P3P policies on a Web site, a company or organization does not make any statements about the privacy practices associated with other Web resources not mentioned in their policy reference file, with other online activities that do not involve data collected on Web sites covered by their P3P policy, or with offline activities that do not involve data collected on Web sites covered by their P3P policy.
In cases where the P3P vocabulary is not precise enough to describe a Web site's practices, sites should use the vocabulary terms that most closely match their practices and provide further explanations (as stated in Section 3.2). However, policies MUST NOT make false or misleading statements.
P3P1.0 user agents can be built into Web browsers, browser plug-ins, or
proxy servers. They can also be implemented as Java applets or JavaScript; or
built into electronic wallets, automatic form-fillers, or other user data
management tools. P3P user agents look for references to a P3P policy at a
well-known location, in P3P headers in HTTP responses, and in P3P
link
tags embedded in HTML content. These references indicate the
location of a relevant P3P policy. User agents can fetch the policy from the
indicated location, parse it, and display symbols, play sounds, or generate
user prompts that reflect a site's P3P privacy practices. They can also
compare P3P policies with privacy preferences set by the user and take
appropriate actions. P3P can perform a sort of "gate keeper" function for data
transfer mechanisms such as electronic wallets and automatic form fillers. A
P3P user agent integrated into one of these mechanisms would retrieve P3P
policies, compare them with user's preferences, and authorize the release of
data only if a) the policy is consistent with the user's preferences and b)
the requested data transfer is consistent with the policy. If one of these
conditions is not met, the user might be informed of the discrepancy and given
an opportunity to authorize the data release themselves.
The P3P1.0 Specification places few requirements on the user interfaces of P3P user agents. Thus user agent implementers may each make their own choices about what words and symbols to present to users to provide information about a Web site's privacy policy. Implementers need not use the definitions found in this specification verbatim in their user interfaces. They should, however, make sure that whatever information they present to the user accurately represents the P3P policies described, as per Appendix 7, "P3P Guiding Principles".
Web sites can implement P3P1.0 on their servers by translating their
human-readable privacy policies into P3P syntax and then publishing the
resulting files along with a policy reference file that indicates the parts of
the site to which the policy applies. Automated tools can assist site
operators in performing this translation. P3P1.0 can be implemented on
existing HTTP/1.1-compliant Web servers without requiring additional or
upgraded software. Servers may publish their policy reference files�at a well-known location, or they may reference
their P3P policy reference files�in HTML/XHTML content using a
link
tag. Alternatively, compatible servers may be configured to
insert a P3P extension header into all HTTP responses that indicates the
location of a site's P3P policy reference file.
Web sites have some flexibility in how they use P3P: they can opt for one P3P policy for their entire site or they can designate different policies for different parts of their sites. A P3P policy MUST cover all data generated or exchanged as part of a site's HTTP interactions with visitors. In addition, some sites may wish to write policies that cover all data an entity collects, regardless of how the data is collected.
Significant sections were removed from earlier drafts of the P3P1.0 specification in order to facilitate rapid implementation and deployment of a P3P first step. A future version of the P3P specification might incorporate those features after P3P1.0 is deployed. Such specification would likely include improvements based on feedback from implementation and deployment experience as well as four major components that were part of the original P3P vision but not included in P3P1.0:
This document, along with its normative references, includes all the specification necessary for the implementation of interoperable P3P applications.
The following key words are used throughout the document and have to be read as interoperability requirements. This specification uses words as defined in RFC2119 [KEY] for defining the significance of each particular requirement. These words are:
The P3P specification defines, with the exception of section 2.2.2, section 2.2.3 and section 4, an XML with namespaces syntax (cf. [XML] and [XML-Name]). In the following, for the sake of brevity we will liberally talk about "XML", meaning the more accurate "XML with namespaces".
A BNF-like notation is also used thorough the specification: the [ABNF] notation used in this specification is specified in RFC2234 and summarized in Appendix 6. However, note that in the case of XML syntax, such ABNF syntax is only a grammar representative used to enhance readability (lacking, for example, all the syntactic flexibilities that are implicitly included in XML, e.g. whitespace rules, quoting using either single quote (') or double quote ("), character escaping, comments, case sensitivity, order of attributes, namespace handling), and as such it has no normative value. All the XML syntax defined in this specification MUST conform to the XML Schema for P3P (see Appendix 4), which, together with the other constraints expressed in this specification using natural language,�constitutes the normative definition.
The (non-normative) DTD provided in Appendix 5 MAY be used to verify that P3P files are valid. However, there are some valid files that may be rejected if checked against the DTD due to their use of namespaces.
As far as the non-XML syntax defined in this specification is concerned (section 2.2.2 defining P3P's HTTP header, section 2.2.3 defining usage of P3P in HTML, and section 4 defining compact policies), instead, the ABNF notation (together with the other constraints expressed in this specification using natural language) constitutes�the normative definition.
user.home-info.postal
". The
P3P1.0 base data schema specifies a number of data sets.DATASCHEMA
element. P3P1.0 defines a standard data schema
called the P3P base data schema.Locating a P3P policy is one of the first steps in the operation of the P3P protocol. Services use policy references to state what policy applies to a specific URI or set of URIs. User agents use policy references to locate the privacy policy that applies to a Web resource, so that they can process that policy for the benefit of their user.
Policy references are used extensively as a performance optimization. P3P policies are typically several kilobytes of data, while a URI that references a privacy policy is typically less than 100 bytes. In addition to the bandwidth savings, policy references also reduce the need for computation: policies can be uniquely associated with URIs, so that a user agent need only parse and process a policy once rather than process it with every document to which the policy applies. Furthermore, by placing the information about relevant policies in a centralized location, Web site administration is simplified.
A policy reference file is used to associate P3P policies with certain regions of URI-space. The policy reference file is an XML with namespaces (see [XML] and [XML-Name]) file that can specify the policy for a single Web document, portions of a Web site, or for an entire site. The policy reference file may refer to one or more P3P policies; this allows for a single reference file to cover an entire site, even if different P3P policies apply to different portions of the site.The policy reference file is used to make any or all of the following statements:
All of these statements are made in the body of the policy reference file.
This section describes the mechanisms used to indicate the location of a policy reference file. Detailed syntax is also given for the supported mechanisms.
The location of the policy reference file can be indicated using one of four mechanisms. The policy reference file
link
tag, orlink
tag, orNote that if user agents support retrieving HTML (resp. XHTML) content over HTTP, they MUST handle mechanisms 1, 2 and 3 (resp. 4) listed above interchangeably. See also the requirements for non-ambiguity.
Policies are applied at the level of resources. A "page" from the user's perspective may be composed of multiple HTTP resources; each may have its own P3P policy associated with it. As a practical note, however, placing many different P3P policies on different resources on a single page may make rendering the page and informing the user of the relevant policies difficult for user agents. Additionally, services are recommended to attempt to craft their policy reference files such that a single policy reference file covers any given "page"; this will speed up the user's browsing experience.
For a user agent to process the policy that applies to a given resource, it must locate the policy reference file for that resource, fetch the policy reference file, parse the policy reference file, fetch any required P3P policies, and then parse the P3P policy or policies.
This document does not specify how P3P policies may be associated with Web resources retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with resources retrieved using other protocols. Furthermore, additional methods of associating P3P policies with HTTP resources may be developed in the future.
Web sites using P3P MAY (and, are strongly encouraged to)�place a policy
reference file in a "well-known" location. To do this, a policy reference file
would be made available on the site at the path /w3c/p3p.xml
.
Note that sites are not required to use this mechanism; however, by using this mechanism, sites can ensure that their P3P policy will be accessible to user agents before any other resources are requested from the site. This will reduce the need for user agents to access the site using safe zone practices. Additionally, if a site chooses to use this mechanism, the policy reference file located in the well-known location is not required to cover the entire site. For example, sites where not all of the content is under the control of a single organization MAY choose not to use this mechanism, or MAY choose to post a policy reference file which covers only a limited portion of the site.
Use of the well-known location for a policy reference file does not preclude use of other mechanisms for specifying a policy reference file. Portions of the site MAY use any of the other supported mechanisms to specify a policy reference file, so long as the non-ambiguity requirements are met.
For example, imagine a shopping-mall Web site run by the MallExample
company. On their Web site (mall.example.com
), companies offering
goods or services at the mall would get a company-specific subtree of the
site, perhaps in the path /companies/company-name
. The
MallExample company may choose to put a policy reference file in the
well-known location which covers all of their site except the
/companies
subtree. Then if the ShoeStoreExample company has some
content in /companies/shoestoreexample
, they could use one of the
other mechanisms to indicate the location of a policy reference file covering
their portion of the mall.example.com
site.
One case where using the well-known location for policy reference files is
expected to be particularly useful is in the case of a site which has divided
its content across several hosts. For example, consider a site which uses a
different logical host for all of its Web-based applications than for its
static HTML content. The other mechanisms allowed for specifying the location
of a policy reference file require that some URI on the host being accessed
must be fetched to locate the policy reference file. However, the well-known
location mechanism has no such requirement. Consider the example of an HTML
form located on www.example.com
. Imagine that the action URI on
that form points to server cgi.example.com
. The policy reference
file that covers the form is unable to make any statements about the action
URI that processes the form. However, the site administrator publishes a
policy reference file at http://cgi.example.com/w3c/p3p.xml
that
covers the action URI, thus enabling a user agent to easily locate the P3P
policy that applies to the action URI before submitting the form contents.
Any document retrieved by HTTP MAY point to a policy reference file through
the use of a new response header, the P3P
header ([P3P-HEADER]). If a site is using P3P headers, it SHOULD
include this on responses for all appropriate request methods, including
HEAD
and OPTIONS
requests.
The P3P header gives one or more comma-separated directives. The syntax follows:
| [1] | p3p-header |
= |
`P3P: ` p3p-header-field *(`,` p3p-header-field) |
| [2] | p3p-header-field |
= |
policy-ref-field | compact-policy-field | extension-field |
| [3] | policy-ref-field |
= |
`policyref="` URI-reference `"` |
| [4] | extension-field |
= |
token [`=` (token | quoted-string) ] |
Here, URI-reference is defined
as per RFC 2396 [URI], token and
quoted-string are defined by [HTTP1.1]. |
In keeping with the rules for other HTTP headers, the name of the P3P header may be written with any casing. The contents should be specified using the casing precisely as specified in this document.
The policyref
directive gives a URI which specifies the
location of a policy reference file which may reference the P3P policy
covering the document that pointed to the reference file, and possibly others
as well. When the policyref
attribute is a relative URI, that URI
is interpreted relative to the request URI. Note that fetching the URI given
in the policyref
directive MAY result in a 300-class HTTP return
code (redirection); user agents MUST interpret those redirects with normal
HTTP semantics. Services should note, of course, that use of redirects will
increase the time required for user agents to find and interpret their
policies. The policyref
URI MUST NOT be used for any other
purpose beyond locating and referencing P3P policies.
The compact-policy-field
is used to specify "compact
policies". This is described in Section 4.
User agents which find unrecognized directives (in the
extension-field
s) MUST ignore the unrecognized directives. This
is to allow easier deployment of future versions of P3P.
1. Client makes a GET
request.
GET /index.html HTTP/1.1 Host: catalog.example.com Accept: */* Accept-Language: de, en User-Agent: WonderBrowser/5.2 (RT-11)
2. Server returns content and the P3P
header pointing to the
policy of the resource.
HTTP/1.1 200 OK P3P: policyref="http://catalog.example.com/P3P/PolicyReferences.xml" Content-Type: text/html Content-Length: 7413 Server: CC-Galaxy/1.3.18
link
TagServers MAY serve HTML content with embedded link
tags (cf.
[HTML]) that indicate the location of the relevant P3P
policy reference file. This use of P3P does not require any change in the
server behavior.
The link
tag encodes the policy reference information that
could be expressed using the P3P
header. The link
tag takes the following form (here, we just produce one possible ABNF format
for the link tag, and suppose the [HTML] syntax rules can
be used when using such a tag into an HTML file):
| [5] | p3p-link-tag |
= |
`<link rel="P3Pv1" href="` URI `">` |
Here, URI is defined as per RFC 2396 [URI]. |
When the href
attribute is a relative URI, that URI is
interpreted relative to the request URI.
In order to illustrate with an example the use of the link
tag, we consider the policy reference expressed in Example 2.1 using HTTP headers. That example can be
equivalently�expressed using the link tag with the following piece of
HTML:
<link rel="P3Pv1" href="http://catalog.example.com/P3P/PolicyReferences.xml">
Finally, note that since the p3p-link-tag
is embedded in an
HTML document, its character encoding will be the same as that of the HTML
document. In contrast to P3P policy and policy reference documents (see section 2.3 and section 3
below), the p3p-link-tag
need not be encoded using [UTF-8]. Note also that the link
tag is not case
sensitive.
link
tagCorrespondingly to the HTML link
tag, P3P also supports XHTML
(cf. [XHTML-MOD]). Servers MAY serve XHTML content
that, using the XHTML Link Module (cf. Section
5.19 of [XHTML-MOD]), indicates the location of
the relevant P3P policy reference file with an embedded XHTML
link
tag. Like in the HTML case, an XHTML link
tag
can be used to encode the policy reference information that could be expressed
using the P3P
header, by:
rel
attribute to "P3Pv1
"href
attribute to the URI of the relevant P3P
policy reference fileThe mechanisms described here MAY be used for HTTP transactions over any underlying protocol. This includes plain-text HTTP over TCP/IP connections or encrypted HTTP over SSL connections, as well as HTTP over any other communications protocol designers wish to implement.
URIs MAY contain network port numbers, as specified in RFC 2396 [URI]. For the purposes of P3P, different ports on a single host MUST be considered to be separate "sites". Thus, for example, the policy reference file at the well-known location for www.example.com on port 80 (http://www.example.com/w3c/p3p.xml) would not give any information about the policies which apply to www.example.com when accessed over SSL (as the SSL communication would take place on a different port, 443 by default).
This document does not specify how P3P policies may be associated with resources retrieved by means other than HTTP. However, it does not preclude future development of mechanisms for associating P3P policies with resources retrieved over other protocols. Furthermore, additional methods of associating P3P policies with resources retrieved using HTTP may be developed in the future.
This section explains the contents of policy reference files in detail.
Consider the case of a Web site wishing to make the following statements:
/P3P/Policies.xml#first
applies to the entire
site, except resources whose paths begin with /catalog
,
/cgi-bin
, or /servlet
./P3P/Policies.xml#second
applies to all
resources whose paths begin with /catalog
./P3P/Policies.xml#third
applies to all resources
whose paths begin with /cgi-bin
or /servlet
,
except for /servlet/unknown
./servlet/unknown
.These statements can be represented by the following XML:
<META xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY-REFERENCES> <EXPIRY max-age="172800"/> <POLICY-REF about="/P3P/Policies.xml#first"> <INCLUDE>/*</INCLUDE> <EXCLUDE>/catalog/*</EXCLUDE> <EXCLUDE>/cgi-bin/*</EXCLUDE> <EXCLUDE>/servlet/*</EXCLUDE> </POLICY-REF> <POLICY-REF about="/P3P/Policies.xml#second"> <INCLUDE>/catalog/*</INCLUDE> </POLICY-REF> <POLICY-REF about="/P3P/Policies.xml#third"> <INCLUDE>/cgi-bin/*</INCLUDE> <INCLUDE>/servlet/*</INCLUDE> <EXCLUDE>/servlet/unknown</EXCLUDE> </POLICY-REF> </POLICY-REFERENCES> </META>
Note this example also includes via EXPIRY
a relative expiry time in the
document (cf. Section <IP_ADDRESS>.2).
This section defines the syntax and semantics of P3P policy reference files. All policy reference files MUST be encoded using [UTF-8]. P3P servers MUST encode their policy reference files using this syntax.
A policy reference file has the META
element as root. It may
contain multiple POLICY-REF
elements. If it does contain more
than one element, they MUST be processed by user agents in the order given in
the file. When a user agent is attempting to determine what policy applies to
a given URI, it MUST use the first POLICY-REF
element in the
policy reference file which applies to that URI.
Note that each POLICY-REF
may contain multiple
INCLUDE
, EXCLUDE
, METHOD
,
COOKIE-INCLUDE
, and COOKIE-EXCLUDE
elements and that
all of these elements within a given POLICY-REF
MUST be
considered together to determine whether the POLICY-REF
�applies
to a given URI. Thus, it is not sufficient to find an INCLUDE
element that matches a given URI, as EXCLUDE
or
METHOD
elements may serve as modifiers that cause the
POLICY-REF
not to match.
Policy reference files make statements about what policy applies to a given
URI. Policy reference files support a simple wildcard character to allow
making statements about regions of URI-space. The character asterisk
('*
') is used to represent a sequence of 0 or more of any
character. No other special characters (such as those found in regular
expressions) are supported.
Note that since the asterisk is also a legal character in URIs ([URI]), some special conventions have to be followed when encoding such "extended URIs" in a policy reference file:
*
's in URIs MUST be escaped in policy
reference files (i.e., they MUST be represented as
"%2A
"). Any '*
' present in a URI within a
policy reference file will be taken as representing the asterisk
wildcard character.*
' present as the asterisk
wildcard character.URI escaping and unescaping is very much dependant on the actual scheme used, and might even differ between individual components within a single scheme, so no simple rule for which characters need to be escaped can be given here. Please refer directly to [URI] for details on the standard escaping process. Note that P3P user agents MAY ignore any URI pattern that does not conform to [URI].
The wildcard character MAY be used in the INCLUDE
and
EXCLUDE
elements, in the COOKIE-INCLUDE
and
COOKIE-EXCLUDE
elements, and in the HINT
element.
META
and
POLICY-REFERENCES
elements<META>
META
element contains a complete policy reference
file. Optionally, one POLICIES
element can follow.
META
can also contain one or more one or more EXTENSION
elements (cf. section 3.5),�as well as an xml:lang
attribute (see section 2.4.2), to indicate the
language in which its content is expressed.<POLICY-REFERENCES
>POLICY-REF
(policy
reference) elements. It MAY also contain one EXPIRY
element (indicating
their expiration time), one or more HINT
element, and one or more EXTENSION
element (cf. section 3.5).| [6] | prf |
= |
`<META xmlns="http://www.w3.org/2002/01/P3Pv1"` [xml-lang] `>` *extension policyrefs [policies] *extension "</META>" |
| [7] | policyrefs |
= |
"<POLICY-REFERENCES>" [expiry] *policyref *hint *extension "</POLICY-REFERENCES>" |
Here PCDATA is defined in [XML]. |
EXPIRY
elementIt is desirable for servers to inform user agents about how long they can use the claims made in a policy reference file. By enabling clients to cache the contents of a policy reference file, it reduces the time required to process the privacy policy associated with a Web resource. This also reduces load on the network. In addition, clients that don't have a valid policy reference file for a URI will need to use "safe zone" practices for their requests. If clients have policy reference files that they know are still valid, then they can make more informed decisions on how to proceed.
In order to achieve these benefits, policy reference files SHOULD contain
an EXPIRY
element, which indicates the lifetime of the policy
reference file. If the policy reference file does not contain an
EXPIRY
element, then it defaults to 24-hour lifetime.
The lifetime of a policy reference file tells user agents how long they can rely on the claims made in the policy reference file. By setting the lifetime of a policy reference file, the publishing site agrees that the policies mentioned in the policy reference file are appropriate for the lifetime of the policy reference file. For example, if a policy reference file has a lifetime of 3 days, then a user agent need not reload that file for 3 days, and can assume that the references made in that policy reference file are good for 3 days. All of the policy references made in a single policy reference file will receive the same lifetime. The only way to specify different lifetimes for different policy references is to use separate policy reference files.
The same mechanism used to indicate the lifetime of a policy reference file
is also used to indicate the lifetime of a P3P policy. Thus P3P
POLICIES
elements SHOULD have an EXPIRY
element
associated with them as well. This lifetime applies to all P3P policies
contained within that POLICIES
element. If there is no
EXPIRY
element associated with a P3P policy, then it defaults to
24-hour lifetime.
When picking a lifetime for policies and policy reference files, sites need to pick a lifetime which balances two competing concerns. One concern is that the lifetime ought to be long enough to allow user agents to receive significant benefits from caching. The other concern is that the site would like to be able to change their policy for new data collection without waiting for an extremely long lifetime to expire. It is expected that lifetimes in the range of 1-7 days would be a reasonable balance between these two competing desires. Sites also need to remember the policy update requirements when updating their policies.
When a policy reference file has expired, the information in the policy reference file MUST NOT be used by a user agent until that user agent has successfully revalidated the policy reference file, or has fetched a new copy of the policy reference file.
Note that while user agents are not obligated to revalidate policy reference files or policy files that have not expired, they MAY choose to revalidate those files before their expiry period has passed in order to reduce the need for using "safe zone" practices. A valid P3P user agent implementation does not need to contain a cache for policies and policy reference files, though the implementation will have better performance if it does.
EXPIRY
elementThe EXPIRY
element can be used in a policy reference file
and/or in a POLICIES
element to state how long the policy
reference file (or policies) remains valid. The expiry
is given as either an absolute expiry time, or a relative expiry time. An
absolute expiry time is a time, given in GMT, until which the policy reference
file (or policies) is valid. A relative expiry time
gives a number of seconds for which the policy reference file (or policies) is valid. This expiry time is relative to the
time the policy reference file (or policies) was
requested or last revalidated by the client. This computation MUST be done
using the time of the original request or revalidation, and the current time,
with both times generated from the client's clock. Revalidation is defined in
section 13.3 of [HTTP1.1].
The minimum amount of time for any relative expiry time is 24 hours, or 86400 seconds. Any relative expiration time shorter than 86400 seconds MUST be treated as being equal to 86400 seconds in a client implementation. If a client encounters an absolute expiration time that is in the past, it MUST act as if NO policy reference file (or policy) is available. See section 2.4.7 "Absence of Policy Reference File" for the required procedure in such cases.
| [8] | expiry |
= |
"<EXPIRY" (absdate|reldate) "/>" |
| [9] | absdate |
= |
`date="` HTTP-date `"` |
| [10] | reldate |
= |
`max-age="` delta-seconds `"` |
| Here, HTTP-date is defined in section 3.3.1 of [HTTP1.1], and delta-seconds is defined in section 3.3.2 of [HTTP1.1]. |
In a real-world network, there may be caches which will cache the contents of policies and policy reference files. This is good for increasing the overall network performance, but may have deleterious effects on the operation of P3P if not used correctly. There are two specific concerns:
HTTP 1.1 [HTTP1.1] contains powerful cache-control mechanisms to allow clients to place requirements on the operations of network caches; these mechanisms can resolve the problems mentioned above. The specific method will be discussed below.
HTTP 1.0, however, does not provide those more sophisticated cache control
mechanisms. An HTTP 1.0 caching proxy�will, in all likelihood, compute a cache
lifetime for the policy reference file (or policies) based on the file's
last-modified date; the resulting cache lifetime could be significantly longer
than the lifetime specified by the EXPIRY
element. The caching
proxy�could then serve the policy reference file (or policies) to clients
beyond the lifetime in the EXPIRY
; the result would be that
user-agents would receive a useless policy reference file (or policies).
The second problem with an HTTP 1.0 caching proxy is that a user agent has no way to know how long the reference file may have been stored by the caching proxy. If the policy reference file (or policies) relies on relative expiry, it would then be impossible for the user agent to determine if the reference file's lifetime has already expired, or when it will expire.
Thus, if a user agent is requesting a policy reference file or a policy, and does not know for certain that there are no HTTP 1.0 caches in the path to the origin server, then the request MUST force an end-to-end revalidation. This can be done with the Pragma: no-cache HTTP request-header. Note that neither HTTP nor P3P define a way to determine if there is a HTTP 1.0-compliant cache in any given network path, so unless the user agent has this information derived from an outside source, it MUST force the end-to-end revalidation.
If the user agent has some way to know that all caches in the network path to the origin server are compliant with HTTP 1.1 (or that there are no caches in the network path to the origin server), then the client MAY do the following instead of forcing an end-to-end revalidation:
Note that it is impossible for a client to accurately predict the amount of latency that may affect an HTTP request. Thus, if the policy reference file covering a request is going to expire soon, clients MAY wish to consider warning their users and/or revalidating the policy reference file before continuing with the request.
The following situations have their semantics specifically defined:
EXPIRY
element, the first one takes precedence for determining the lifetime of
the policy reference file.POLICY-REF
elementA policy reference file may refer to multiple P3P policies, specifying
information about each. The POLICY-REF
element describes
attributes of a single P3P policy. Elements within the POLICY-REF
element give the location of the policy and specify the areas of URI-space
(and cookies) that each policy covers.
POLICY-REF
about
(mandatory
attribute)name
attribute), and the URI part denotes the URI where the
policy resides (a policy file, or a policy reference file, see Section 3.2). If this is a relative URI reference,
it is interpreted relative to the URI of the policy reference file it
resides in.| [11] | policy-ref |
= |
`<POLICY-REF about="` URI-reference `">` *include *exclude *cookie-include *cookie-exclude *method-element *extension `</POLICY-REF>` |
Here, URI-reference is defined as per RFC 2396 [URI]. |
INCLUDE
and
EXCLUDE
elementsEach INCLUDE
or EXCLUDE
element specifies one
local URI or set of local URIs. A set of URIs is specified if the wildcard character '*' is used in the
URI-pattern. These elements are used to specify the portion of the Web site
that is covered by the policy referenced by the enclosing
POLICY-REF
element.
When INCLUDE
(and optionally, EXCLUDE
) elements
are present in a POLICY-REF
element, it means that the policy
specified in the about
attribute of the POLICY-REF
element applies to all the URIs at the requested host corresponding to the
local-URI(s) matched by any of the INCLUDE
s, but not matched by
an EXCLUDE
element.
A policy referenced in a policy reference file can be applied only to URIs
on the DNS (Domain Name System) host that references it. Thus, for example, a
policy reference file at the well-known location of host www.example.com can
apply policies only to resources on www.example.com. However, if
foo.example.com includes a P3P HTTP header in its responses that references a
policy reference file on bar.example.com, that policy reference file would be
applied to resources on foo.example.com (not bar.example.com or
www.example.com). The same policy reference file might be referenced in P3P
HTTP headers sent by multiple hosts, in which case it may be applied to each
host that references it. The INCLUDE
and EXCLUDE
elements MUST specify URI patterns relative to the root of the DNS host to
which they are applied. This requirement does NOT apply to the location of the
P3P policy file (the about attribute on the POLICY-REF
element).
If a METHOD
element (section
<IP_ADDRESS>) specifies one or more methods for an enclosing policy reference,
it follows that all methods not mentioned are consequently
not covered by this policy. In the case that this is the only policy
reference for a given URI prefix, user agents MUST assume that NO policy is in
effect for all methods NOT mentioned in the policy reference file. It is legal
but pointless to supply a METHOD
element without any
INCLUDE
or COOKIE-INCLUDE
elements.
It is legal, but pointless, to supply an EXCLUDE
element
without any INCLUDE
elements; in that case, the
EXCLUDE
element MUST be ignored by user agents.
Note that the set of URIs specified with INCLUDE
and
EXCLUDE
does not include cookies that might be set or replayed
when requesting one of such URIs: in order to associate policies with cookies,
the COOKIE-INCLUDE
and
COOKIE-EXCLUDE
elements are needed.
| [12] | include |
= |
"<INCLUDE>" relativeURI "</INCLUDE>" |
| [13] | exclude |
= |
"<EXCLUDE>" relativeURI "</EXCLUDE>" |
Here, relativeURI is defined as per RFC 2396 [URI], with the addition that the '* '
character is to be treated as a wildcard, as defined in section <IP_ADDRESS>.2. |
HINT
elementPolicy reference hints are a performance optimization that can be used
under certain conditions. A site may declare a policy reference for itself
using the well-known location, the P3P response header, or the HTML/XHTML
link
tag. It MAY further provide a hint to additional policy
references, such as those declared by other sites.
For example, an HTML page might hint at policy references for its hyperlinks, embedded content, and action URIs. User agents MAY use the hint mechanism to discover policy reference files before requesting the affected URIs when the policy references are not available from the well-known location.
User agents which use hints to retrieve policies MUST NOT apply them to any site other than the one which contains the hinted policy reference file.
Any policy reference file MAY contain zero or more policy reference hints.
Each hint is contained in a HINT
element with two attributes,
scope
and path
.
The scope
attribute is used to specify a URI scheme and
authority to which the hinted policy reference can be applied. If the
authority component (cf. [URI]) is a server component
(e.g., a hostname or IP address) the host part of the authority MAY begin with
a wildcard, as defined in Section <IP_ADDRESS>.2.
The scope
attribute MUST NOT contain a wildcard in any other
position, MUST be encoded according to the conventions in Section <IP_ADDRESS>.2,
and MUST NOT contain a path, query or fragment URI component. �Additionally,
if the authority is a server, it SHOULD NOT contain a userinfo part.
For example, legal values for scope
include:
http://www.example.com
http://www.example.com:81
http://*.example.com
ftp://ftp.example.org
The following are illegal values for the scope
attribute:
http://www.*.com � � � �
; the wildcard can only be at the
starthttp://www.example.com/ �
; the trailing slash is not
allowedwww.example.com � � � � �
; the scheme must be stated*://www.example.com � � �
; the scheme cannot contain a
wildcardhttp://www.example.com:*
; the port cannot contain a
wildcardThe path
attribute is used to locate the policy reference file
on the hinted site. It is a relative URI whose base is the URI scheme and
authority matched in the scope
attribute. The path
attribute MUST NOT be an absolute URI, so that the policy reference file is
always retrieved from the same site that it is applied to.
Example 2.3:
<HINT scope="http://www.example.org" path="/mypolicy/p3.xml" /> <HINT scope="http://www.example.net:81" path="/w3c/prf.xml" /> <HINT scope="http://*.shop.example.com" path="/w3c/prf.xml" />
| [14] | hint |
= |
`<HINT scope="` scheme ( `://` | `:/` ) authority `" path="` relativeURI `/>` |
Here, scheme , authority and
relativeURI are taken from RFC 2965 [STATE]. |
COOKIE-INCLUDE
and
COOKIE-EXCLUDE
elementsThe COOKIE-INCLUDE
and COOKIE-EXCLUDE
elements
are used to associate policies to cookies (cf. [COOKIES] and [STATE]).
A cookie policy MUST cover any data (within the scope of P3P) that is
stored in that cookie or linked via that cookie. It MUST also reference all
purposes associated with data stored in that cookie or enabled by that cookie.
In addition, any data/purpose stored or linked via a cookie MUST also be put
in the cookie policy. In addition, if that linked data is collected by HTTP,
then the policy that covers that GET
/POST
/whatever
request must cover that data collection. For example, when CatalogExample asks
customers to fill out a form with their name, billing, and shipping
information, the P3P policy that covers the form submittal will disclose that
CatalogExample collects this data and explain how it is used. If
CatalogExample sets a cookie so that it can recognize its customers and
observe their behavior on its Web site, it would have a separate policy for
this cookie. However, if this cookie is also linked to the user's name,
billing, and shipping information -- perhaps so CatalogExample can generate
custom catalog pages based on where the customer lives -- then that data must
also be disclosed in the cookie policy.
For the purpose of this specification, state management mechanisms use
either SET-COOKIE
or SET-COOKIE2
headers, and
cookie-namespace is defined as the value of the NAME, VALUE, Domain and Path
attributes, specified in [COOKIES] and [STATE].
Each COOKIE-INCLUDE
or COOKIE-EXCLUDE
element can
be used to match (similarly to INCLUDE
and EXCLUDE
)
the NAME, VALUE, Domain and Path components of a cookie, expressing the
cookies which are covered by the policy specified by the about
attribute when the cookies are set from the resources on the Web site where
the policy reference file resides:
COOKIE-INCLUDE
(resp.
COOKIE-EXCLUDE
)name
,
value
, domain
and path
attributesname
value
domain
path
If the value of the domain
attribute is set to the dot
character (".
"), the domain will match only cookies that omit the
domain
attribute (and thus have domain equivalent to the request
host as per RFC 2965 ([STATE]).
Cookies that omit the path attribute have the default path of the request
URI that generated the set-cookie response as per RFC 2965 [STATE]. The path
attribute of a
COOKIE-INCLUDE
should be matched against this default value if a
cookie omits the path
attribute.
All four attributes are optional. If an attribute is absent, the
COOKIE-INCLUDE
(resp. COOKIE-EXCLUDE
) will match
cookies that have that attribute set to any value.
When COOKIE-INCLUDE
(and optionally,
COOKIE-EXCLUDE
) elements are present in a POLICY-REF
element, the policy specified in the about
attribute of the
POLICY-REF
element applies to every cookie that �is matched by
any COOKIE-INCLUDE
's, and not matched by a
COOKIE-EXCLUDE
element.
User agents MUST interpret COOKIE-INCLUDE
and
COOKIE-EXCLUDE
elements in a policy reference file to determine
the policy that applies to cookies set by or replayed to the host to which the
policy reference file applies. While the domain attribute of a
COOKIE-INCLUDE
may match more broadly (for example, if the domain
attribute is omitted it defaults to matching any domain value), user agents
MUST limit their application of the policy to domains that could be legally
used in a cookie set by the host to which the policy reference file applies.
For example, if abc.xyz.example.com declares a policyref with
<COOKIE-INCLUDE domain="*.xyz.*ple.com"/>
, this would be
matched to cookies with domains such as .abc.xyz.example.com and
.xyz.example.com, but not .example.com or .xyz.sample.com.
A P3P policy can be associated with a cookie by the host that set that
cookie as well as by any or all of the hosts to which it might be replayed. A
user agent MAY fetch a cookie policy at the time a cookie is set and apply it
later when the cookie is replayed, perhaps to other hosts in the domain. A
user agent MAY request a policy reference file from a host before replaying a
cookie to that host, and if the policy reference file contains an appropriate
COOKIE-INCLUDE
, a policy will be applied to that cookie even if
the cookie was not set by that host. Any host to which the cookie may be
replayed MUST be able to honor all the policies associated with the cookie,
regardless of whether that host declares a policy for that cookie. Thus sites
that set cookies that may be replayed to multiple hosts within a domain need
to coordinate to make sure all the hosts can follow the declared policy. In
addition, sites should be cautious with their use of wildcards to make sure
that they do not inadvertently apply a policy to cookies to which it should
not be applied (including previously set cookies that are still in use and
cookies set by other hosts in the domain).
The policy that applies to a cookie applies until the policy expires, even if the associated policy reference file expires prior to policy expiry (but after the cookie was set). If the policy associated with a cookie has expired, then the user agent SHOULD reevaluate the cookie policy before sending the cookie. In addition, user agents MUST use only non-expired policies and policy reference files when evaluating new set-cookie events.
Example 2.4 states that /P3P/Policies.xml#first
applies to all
cookies.
Example 2.4:
<META xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY-REFERENCES> ��� <POLICY-REF about="/P3P/Policies.xml#first"> <COOKIE-INCLUDE name="*" value="*" domain="*" path="*"/> ��� </POLICY-REF> </POLICY-REFERENCES> </META>
Example 2.5 states that /P3P/Policies.xml#first
applies to all
cookies, except cookies with the cookie name value of
�"obnoxious-cookie
", a domain value of
".example.com
", and a path value of "/
", and that
/P3P/Policies.xml#second
applies to all cookies with the cookie
name of "obnoxious-cookie
", a domain value of
".example.com
", and a path value of "/
".
Example 2.5:
<META xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY-REFERENCES> ��� <POLICY-REF about="/P3P/Policies.xml#first"> <COOKIE-INCLUDE name="*" value="*" domain="*" path="*"/> <COOKIE-EXCLUDE name="obnoxious-cookie" value="*" domain=".example.com" path="/"/> </POLICY-REF> <POLICY-REF about="/P3P/Policies.xml#second"> <COOKIE-INCLUDE name="obnoxious-cookie" value="*" domain=".example.com" path="/"/> ��� </POLICY-REF> </POLICY-REFERENCES> </META>
| [15] | cookie-include |
= |
"<COOKIE-INCLUDE" [` name="` token `"`] ; matches the cookie's NAME [` value="` token `"`] ; matches the cookie's VALUE [` domain="` token `"`] ; matches the cookie's Domain [` path="` token `"`] ; matches the cookie's Path "/>" |
| [16] | cookie-exclude |
= |
"<COOKIE-EXCLUDE" [` name="` token `"`] ; matches the cookie's NAME [` value="` token `"`] ; matches the cookie's VALUE [` domain="` token `"`] ; matches the cookie's Domain [` path="` token `"`] ; matches the cookie's Path "/>" |
Here, token , NAME ,
VALUE , Domain and Path are
defined as per RFC
2965 [STATE], with the addition that the
'* ' character is to be treated as a wildcard, as defined
in section <IP_ADDRESS>.2. |
Note that [STATE] states default values for the
domain and path attributes of cookies: these should be used in the comparison
if those attributes are not found in a specific cookie. Also, conforming to
[STATE], if an explicitly specified
Domain
value does not start with a full stop (".
"),
the user agent MUST prepend a full stop for it; and, note that every
Path
begins with the "/
" character.
METHOD
elementBy default, a policy reference applies to the stated URIs regardless of the
method used to access the resource. However, a Web site may wish to define
different P3P policies depending on the method to be applied to a resource.
For example, a site may wish to collect more data from users when they are
performing PUT
or DELETE
methods than when
performing GET
methods.
The METHOD
element in a policy reference file is used to state
that the enclosing policy reference only applies when the specified methods
are used to access the referenced resources. The METHOD
element
may be repeated to indicate multiple applicable methods. If the
METHOD
element is not present in a POLICY-REF
element, then that POLICY-REF
element covers the resources
indicated regardless of the method used to access them.
So, to state that /P3P/Policies.xml#first
applies to all
resources whose paths begin with /docs/
for GET
and
HEAD
methods, while /P3P/Policies.xml#second
applies
for PUT
and DELETE
methods, the following policy
reference would be written:
Example 2.6:
<META xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY-REFERENCES> <POLICY-REF about="/P3P/Policies.xml#first"> <INCLUDE>/docs/*</INCLUDE> <METHOD>GET</METHOD> <METHOD>HEAD</METHOD> </POLICY-REF> <POLICY-REF about="/P3P/Policies.xml#second"> <INCLUDE>/docs/*</INCLUDE> <METHOD>PUT</METHOD> <METHOD>DELETE</METHOD> </POLICY-REF> </POLICY-REFERENCES> </META>
Note that HTTP requires the same behavior for GET
and
HEAD
requests, thus it is inappropriate to specify different P3P
policies for these methods. The syntax for the METHOD
element
is:
| [17] | method-element |
= |
`<METHOD>` Method `</METHOD>` |
Here, Method is defined in the section
5.1.1 of [HTTP1.1]. |
Finally, note that the METHOD
element is designed to be used
in conjunction with INCLUDE
or COOKIE-INCLUDE
elements. A METHOD
element by itself will never apply a
POLICY-REF
to a URI.
A policy reference file specifies the policy which applies to a given URI.
In other words, the indicated policy describes all effects of dereferencing
the given URI (in some cases, with the appropriately specified
METHOD
).
There is a general rule which describes what it means for a P3P policy to
cover a URI: the referenced policy MUST cover actions that the user's
client software is expected to perform as a result of requesting that URI.
Obviously, the policy must describe all data collection performed by site as a
result of processing the request for the URI. Thus, if a given URI is covered
for terms of GET
requests, then the policy given by the policy
reference file MUST describe all data collection performed by the site when
that URI is dereferenced. Likewise, if a URI is covered for POST
requests, then any data collection that occurs as a result of POSTing a form
or other content to that URI MUST be described by the policy.
The concept of "actions that the client software is expected to perform" includes the setting of client-side cookies or other state-management mechanisms invoked by the response. If executable code is returned when a URI is requested, then the P3P policy covering that URI MUST cover certain actions which will occur when that code is executed. The covered actions are any actions which could take place without the user explicitly invoking them. If explicit user action causes data to be collected, then the P3P policy covering the URI for that action would disclose that data collection.
Some specific examples:
Forms deserve special consideration, as they often link to CGI scripts or
other server-side applications in their action URIs (the action URI
is the URI given in the action attribute of the HTML
<FORM>
element, as defined in section 17.3 of [HTML]). It is often the case that those action URIs are
covered by a different policy than the form itself.
If a user agent is unable to find a matching include-rule for a given
action URI in the policy reference file that was referenced from the page, it
SHOULD assume that no policy is in effect. Under these circumstances,
user agents SHOULD check the well-known
location on the host of the action URI to attempt to find a policy
reference file that covers the action URI. If this does not provide a P3P
policy to cover the action URI, then a user agent MAY try to retrieve the
policy reference file by using the HINT
mechanism on the action URI, and/or by issuing a HEAD
request
to the action URI before actually submitting any data in order to find the
policy in effect. Services SHOULD ensure that server-side applications can
properly respond to such HEAD
requests and return the
corresponding policy reference link in the headers. In case the underlying
application does not understand the HEAD
request and no
policy has been predeclared for the action URI in question, user agents MUST
assume that no policy is in effect and SHOULD inform the user about
this or take the corresponding actions according to the user's
preferences.
Note that services might want to make use of the
<METHOD>
element in order to declare policies for
server-side applications that only cover a subset of supported methods, e.g.,
POST
or GET
. Under such circumstances, it is
acceptable that the application in question only supports the methods given in
the policy reference file (e.g., PUT
requests need not be
supported). User agents SHOULD NOT attempt to issue a HEAD
request to an action URI if the relevant methods specified in the form's
method
attribute have been properly predeclared in the page's
policy reference file.
In some cases, different data is collected at the same
action URI depending on some selection in the form. For example, a search
service might offer to both search for people (by name and/or email) and
(arbitrary) images. Using a set of radio buttons on the form, a single
server-side application located at one and the same action URI handles both
cases and collects the required information necessary for the search. If a
service wants to predeclare the data collection practices of the server-side
application it MAY declare all of the data collection practices in a
single policy file (using a <INCLUDE>
declaration
matching the action URI). In this case, user agents MUST assume that all data
elements are collected under every circumstance. This solution offers the
convenience of a single policy but might not properly reflect the fact that
only parts of the listed data elements are collected at a time. Services
SHOULD make sure that a simple HEAD
request to the action URI
(i.e., without any arguments, especially without the value of the selected
radio button) will return a policy that covers all cases.
Note that if a form is handled through use of the GET
method,
then the action URI reflects the choice of form elements selected by the user.
In some cases, it will be possible to make use of the wildcard syntax allowed
in policy reference files to specify different policies for different uses of
the same form action-handler URI. Therefore, user agents MUST include the
query-string portion of URIs when making comparisons with INCLUDE
and EXCLUDE
elements in policy reference files.
User agents need to be able to determine unambiguously what policy applies to a given URI. Therefore, sites SHOULD avoid declaring more than one non-expired policy for a given URI. In some rare case sites MAY declare more than one non-expired policy for a given URI, for example, during a transition period when the site is changing its policy. In those cases, the site will probably not be able to determine reliably which policy any given user has seen, and thus it MUST honor all policies (this is also the case for compact policies, cf. Section 4.1 and Section 4.6). Sites MUST be cautious in their practices when they declare multiple policies for a given URI, and ensure that they can actually honor all policies simultaneously.
If a policy reference file at the well-known location declares a non-expired policy for a given URI, this policy applies, regardless of any conflicting policy reference files referenced through HTTP headers or HTML/XHTML link tags.
If an HTTP response header includes references to more than one policy reference file, P3P user agents MUST ignore all references after the first one.
If an HTML (resp. XHTML) file includes HTML (resp. XHTML) link
tag references to more than one policy reference file, P3P user agents MUST
ignore all references after the first one.
If a user agent discovers more than one non-expired P3P policy for a given
URI (for example because a page has both a P3P header and a link
tag that reference different policy reference files, or because P3P headers
for two pages on the site reference different policy reference files that
declare different policies for the same URI), the user agent MAY assume any
(or all) of these policies apply as the site MUST honor all of them.
Multiple language versions (translations) of the same policy can be offered
by the server using the HTTP "Content-Language
" header to
properly indicate that a particular language has been used for the policy.
This is useful so that human-readable fields such as entity and consequence
can be presented in multiple languages. The same mechanism can also be used to
offer multiple language versions for data schemas. Servers SHOULD return a
localized policy in response to an HTTP request with an HTTP
"Accept-Language
" header when a policy matching the given
language preferences is available.
Whenever Content-Language
is used to distinguish policies at
the same URI that are offered in multiple languages, the policies MUST have
the same meaning in each language. Two policies (or two data schemas) are
taken to be identical if
Due to the use of the Accept-Language
mechanism, implementers
should take note that user agents may see different language versions of a
policy or policy reference file despite sending the same
Accept-Language
request header if a new language version of a
policy or data schema has been added.
Finally, language declarations can be also included directly within P3P XML
files: the POLICY
, POLICIES
, META
, and
DATASCHEMA
elements MAY take an xml:lang
attribute
to indicate the language of any human-readable fields they contain
(xml:lang
is normatively defined in section 2.12 of [XML]).
| [18] | xml-lang |
= |
` xml:lang="` language `"` |
Here, language is a language identifier as
defined in [LANG]. |
P3P defines a special set of "safe zone" practices, which SHOULD be used by all P3P-enabled user agents and services for the communications which take place as part of fetching a P3P policy or policy reference file. In particular, requests to the well-known location for policy reference files SHOULD be covered by these "safe zone" practices. Communications covered by the safe zone practices SHOULD have only minimal data collection, and any data that is collected is used only in non-identifiable ways.
To support this safe zone, P3P user agents SHOULD suppress the transmission of data unnecessary for the purpose of finding a site's policy until the policy has been fetched. Therefore safe-zone practices for user agents include the following requirements:
Referer
header in the
safe zoneAccept-Language
HTTP header in the
safe zone. Sending the correct Accept-Language
header will
allow fetching a P3P policy in the user's preferred natural language (if
available), but does expose a certain amount of information about the
identity of the user. User agents MAY wish to allow users to decide when
these headers should be sent.Safe-zone practices for servers include the following requirements:
Referer
header, cookies, user agent information, or other information unnecessary
for responding to requests in the safe zoneAccept-Language
HTTP
header as part of safe-zone operation, the server is free to choose any of
the available translationsNote that the safe zone requirements do not say that sites cannot keep identifiable information -- only that they SHOULD NOT use in an identifiable way any information collected while serving a policy file or policy reference file. Tracking down the source of a denial of service attack, for example, would be a legitimate reason to use this information.
P3P user agents MUST only render or act upon P3P policies and policy reference files that are well-formed XML.
P3P user agents SHOULD only render or act upon P3P policies and policy reference files that conform to the XML schema given in Appendix 4, and user agents SHOULD NOT rely upon any part of a policy or policy reference file that does not conform to this XML schema.
User agents MUST NOT locally modify a P3P policy or policy reference file in order to make it conform to the XML schema.
P3P policies and references to P3P policies SHOULD NOT contain any sensitive information. This means that there are no additional security requirements for transporting a reference to a P3P policy beyond the requirements of the document it is associated with; so, if an HTML document would normally be served over a non-encrypted session, then P3P does not require nor recommend that the document be served over an encrypted session when a reference to a P3P policy is included with that document.
Note that when a Web site changes its P3P policy, the old policy applies to data collected when it was in effect. It is the responsibility of the site to keep records of past P3P policies and policy reference files along with the dates when they were in effect, and to apply these policies appropriately.
If a site wishes to apply a new P3P policy to previously collected data, it MUST provide appropriate notice and opportunities for users to accept the new policy that are consistent with applicable laws, industry guidelines, or other privacy-related agreements the site has made.
If no policy reference file is available for a given site, user agents MUST assume (an empty) policy reference file exists at the well-known location with a 24 hour expiry, and therefore if the user returns to the site after 24 hours, the user agent MUST attempt to fetch a policy reference file from the well-known location again. User agents MAY check the well-known location more frequently, or upon a certain event such as the user clicking a browser refresh button. Sites MAY place a policy reference file at the well-known location that indicates that no policy is available, but set the expiry such that user agents know they need not check every 24 hours.
User agents MAY asynchronously fetch and evaluate P3P policies. That is, P3P policies need not necessarily be fetched and evaluated prior to other HTTP transactions.This behavior may be dependent on the the user's preferences and the type of request being made. Until a policy is evaluated, the user agent SHOULD treat the site as if it has no privacy policy. Once the policy has been evaluated, the user agent SHOULD apply the user's preferences. To promote deterministic behavior, the user agent SHOULD defer application of a policy until a consistent point in time. For example, a Web browser might apply a user's preferences just after the user agent completes a navigation, or when confirming a form submission.
As an aid to sites deploying P3P, several example scenarios are presented, along with descriptions of how P3P is used on those sites.
Scenario 1: Web site basic.example.com uses a variety of images, all of which it hosts. It also includes some forms, which are all submitted directly to the site. This site can declare a single P3P policy for the entire site (or if different privacy policies apply to different parts of the site, it can declare multiple P3P policies). As long as all of the images and form action URIs are in directories covered by the site's P3P policy, user agents will automatically recognize the images and forms as covered by the site's policy.
Scenario 2: Web site busy.example.com uses a content
distribution network called cdn.example.com to host its images so as to reduce
the load on its servers. Thus, all of the images on the site have URIs at
cdn.example.com. CDN acts as an agent to Busy in this situation, and collects
no data other than log data. This log data is used only for Web site and
system administration in support of providing the services that Busy
contracted for. Busy's privacy policy applies to the images hosted by CDN, so
Busy uses the HINT
element in its policy reference file to point
to a suitable policy reference file at CDN, indicating that such images are
covered by example.com P3P policy.
Scenario 3: Web site busy.example.com also has a contract
with an advertising company called clickads.example.com to provide banner ads
on its site. The contract allows Clickads to set cookies so as to make sure
each user does not see a given ad more than three times. Clickads collects
statistics on how many users view each ad and reports them to the companies
whose products are being advertised. But these reports do not reveal
information about any individual users. As was the case in Scenario 2, Busy's
privacy policies applies to these ads hosted by Clickads, so Busy uses the
HINT
element in its policy reference file to point to a suitable
policy reference file at Clickads, indicating that Busy P3P policy applies to
such embedded content served by clickads.example.com. The companies whose
products are being advertised need not be mentioned in the Busy privacy policy
because the only data they are receiving is aggregate data.
Scenario 4: Web site busy.example.com also has a contract
with funchat.example.com to host a chat room for its users. When users enter
the chat room they are actually leaving the Busy site. However, the chat room
has the Busy logo and is actually covered by the Busy privacy policy. In this
instance Funchat is acting as an agent for Busy, but -- unlike the previous
examples -- their content is not embedded in the Busy site. Busy can use the
HINT
element in its policy reference file to point to a suitable
Funchat policy reference file, that indicates that Funchat chat room is
covered by Busy privacy policy, therefore facilitating a smoother transition
to the chat room.
Scenario 5: Web site bigsearch.example.com has a form that
allows users to type in a search query and have it performed on their choice
of search engines located on other sites. When a user clicks the "submit"
button, the search query is actually submitted directly to these search
engines -- the action URI is not on bigsearch.example.com but rather on the
search engine selected by the user. Bigsearch can declare the privacy policies
for these search engines by using the HINT
element to point to
their corresponding policy reference files. So when a user clicks the "submit"
button, their user agent can check its privacy policy before posting any data.
In order to make this search choice mechanism work, Bigsearch might actually
have a form with an action URI on its own site, which redirects to the
appropriate search engine. In this case, the user agent should check the
search engine privacy policy upon receiving the redirect response.
Scenario 6: Web site bigsearch.example.com also has a form that allows users to type in a search query and have it simultaneously performed on ten different search engines. Bigsearch submits the queries, gets back the results from each search engine, removes the duplicates, and presents the results to the user. In this case, the user interacts only with Bigsearch. Thus, the only P3P policy involved is the one that covers the Bigsearch Web site. However, Bigsearch must disclose that it shares the users' search queries with third parties (the search Web sites), unless Bigsearch has a contract with these search engines and they act as agents to Bigsearch.
Scenario 7: Web site bigsearch.example.com also has banner
advertisements provided by a company called adnetwork.example.com. Adnetwork
uses cookies to develop profiles of users across many different Web sites so
that it can provide them with ads better suited to their interests. Because
the data about the sites that users are visiting is being used for purposes
other than just serving ads on the Bigsearch Web site, Adnetwork cannot be
considered an agent in this context. Adnetwork must create its own P3P policy
and use its own policy reference file to indicate what content it applies to.
In addition, Bigsearch may optionally use the HINT
element in its
policy reference file to indicate that the Adnetwork P3P policy reference file
applies to these advertisements. Bigsearch should only do this if Adnetwork
has told it what P3P policy applies to these advertisements and has agreed to
notify Bigsearch if the policy reference needs to be changed.
Scenario 8: Web site busy.example.com uses cookies
throughout its Web site. It discloses a cookie policy, separate from its
regular P3P policy to cover these cookies. It uses the
COOKIE-INCLUDE
element in its policy reference file to declare
the appropriate policy for these cookies. As a performance optimization, it
also makes available a compact policy by sending a P3P header that includes
this compact policy whenever it sets a cookie.
Scenario 9: Web site config.example.com provides a service
in which they optimize various kinds of Web content based on each user's
computer and Internet configuration. Users go to the Config Web site and
answer questions about their computer, monitor, and Internet connection.
Config encodes the responses and stores them in a cookie. Later, when the user
is visiting Busy -- a �Web site that has contracted with Config -- whenever
the browser requests content that can be optimized (certain images, audio
files, etc.), Busy will redirect the user to Config, which will read the
user's cookie, and deliver the appropriate content. In this case, Config
should declare a privacy policy that describes the kinds of data collected and
stored in its cookies, and how that data is used. It should use a
COOKIE-INCLUDE
element in its �policy reference file to declare
the policy for the cookies. It will probably reference Busy's P3P policy for
the actual images or audio files delivered, as it is acting much like CDN acts
in scenario 2. Busy will probably also use HINT
elements in its
policy reference file to reference the policy for the Config-delivered
content.
P3P policies are encoded in XML with namespaces (see [XML] and [XML-Name]). A possible encoding using the RDF data model ([RDF]) is provided in [P3P-RDF].
Section 3.1 begins with an example of an English language privacy policy
and a corresponding P3P policy. P3P policies include general assertions that
apply to the entire policy as well as specific assertions -- called
statements -- that apply only to the handling of particular types of
data referred to by data references. Section 3.2 describes the
POLICY
element and policy-level assertions. Section 3.3 describes
statements and data references.
The following are two examples of English-language privacy policy to be encoded as a P3P policy. Both policies are for one example company, CatalogExample, which has different policies for those browsing their site and those actually purchasing products. Example 3.1. is provided in both English and as a more formal description using P3P element and attribute names.
CatalogExample
4000 Lincoln Ave.
Birmingham, MI 48009 USA
email<EMAIL_ADDRESS>Telephone 248-EXAMPLE<PHONE_NUMBER>)
Data retention:
We purge every two weeks the browsing information that we collect.
Here is Example 3.1 in a more formal description, using the P3P element and attribute names [with the section of the spec that was used cited in brackets for easy reference]:
CatalogExample
4000 Lincoln Ave.
Birmingham, MI 48009 USA
email<EMAIL_ADDRESS>Telephone +1 248-EXAMPLE (+1<PHONE_NUMBER>)
If you choose to purchase an item we will ask you for more information
including:
Also on this page we will give you the option to choose if you would
like to receive email, telephone calls or written service from
CatalogExample or from our carefully selected marketing partners who
maintain similar privacy practices. If you would like to receive these
solicitations simply check the appropriate boxes. You can choose to stop
participating at any time simply by changing your preferences.
Changing and Updating personal information
Consumers can change all of their personal account information by going
to the preferences section of CatalogExample at
http://catalog.example.com/preferences.html. You can change your
address, telephone number, email address, password as well as your
privacy settings.
Cookies
CatalogExample uses cookies only to see if you have been an
CatalogExample customer in the past and, if so, customize services based
on your past browsing habits and purchases. We do not store any personal
data in the cookie nor do we share or sell the any of the information
with other parties or affiliates.
Data retention
We will keep the information about you and your purchases for as long as
you remain our customer. If you do not place an order from us for one
year we will remove your information from our databases.
The following pieces of [XML] capture the information as expressed in the above two examples. P3P policies are statements that are properly expressed as well-formed XML. The policy syntax will be explained in more detail in the sections that follow.
XML Encoding of Example 3.1:
<POLICIES xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY name="forBrowsers" discuri="http://www.catalog.example.com/PrivacyPracticeBrowsing.html" xml:lang="en"> <ENTITY> <DATA-GROUP> <DATA ref="#business.name">CatalogExample</DATA> <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA> <DATA ref="#business.contact-info.postal.city">Birmingham</DATA> <DATA ref="#business.contact-info.postal.stateprov">MI</DATA> <DATA ref="#business.contact-info.postal.postalcode">48009</DATA> <DATA ref="#business.contact-info.postal.country">USA</DATA> <DATA<EMAIL_ADDRESS><DATA ref="#business.contact-info.telecom.telephone.intcode">1</DATA> <DATA ref="#business.contact-info.telecom.telephone.loccode">248</DATA> <DATA ref="#business.contact-info.telecom.telephone.number">3926753</DATA> </DATA-GROUP> </ENTITY> <ACCESS><nonident/></ACCESS> <DISPUTES-GROUP> <DISPUTES resolution-type="independent" service="http://www.PrivacySeal.example.org" short-description="PrivacySeal.example.org"> <IMG src="http://www.PrivacySeal.example.org/Logo.gif" alt="PrivacySeal's logo"/> <REMEDIES><correct/></REMEDIES> </DISPUTES> </DISPUTES-GROUP> <STATEMENT> <PURPOSE><admin/><develop/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <!-- Note also that the site's human-readable privacy policy MUST mention that data is purged every two weeks, or provide a link to this information. --> <DATA-GROUP> <DATA ref="#dynamic.clickstream"/> <DATA ref="#dynamic.http"/> </DATA-GROUP> </STATEMENT> </POLICY> </POLICIES>
XML Encoding of Example 3.2:
<POLICIES xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY name="forShoppers" discuri="http://www.catalog.example.com/Privacy/PrivacyPracticeShopping.html" opturi="http://catalog.example.com/preferences.html" xml:lang="en"> <ENTITY> <DATA-GROUP> <DATA ref="#business.name">CatalogExample</DATA> <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA> <DATA ref="#business.contact-info.postal.city">Birmingham</DATA> <DATA ref="#business.contact-info.postal.stateprov">MI</DATA> <DATA ref="#business.contact-info.postal.postalcode">48009</DATA> <DATA ref="#business.contact-info.postal.country">USA</DATA> <DATA<EMAIL_ADDRESS><DATA ref="#business.contact-info.telecom.telephone.intcode">1</DATA> <DATA ref="#business.contact-info.telecom.telephone.loccode">248</DATA> <DATA ref="#business.contact-info.telecom.telephone.number">3926753</DATA> </DATA-GROUP> </ENTITY> <ACCESS><contact-and-other/></ACCESS> <DISPUTES-GROUP> <DISPUTES resolution-type="independent" service="http://www.PrivacySeal.example.org" short-description="PrivacySeal.example.org"> <IMG src="http://www.PrivacySeal.example.org/Logo.gif" alt="PrivacySeal's logo"/> <REMEDIES><correct/></REMEDIES> </DISPUTES> </DISPUTES-GROUP> <STATEMENT> <CONSEQUENCE> We record some information in order to serve your request and to secure and improve our Web site. </CONSEQUENCE> <PURPOSE><admin/><develop/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#dynamic.clickstream"/> <DATA ref="#dynamic.http.useragent"/> </DATA-GROUP> </STATEMENT> <STATEMENT> <CONSEQUENCE> We use this information when you make a purchase. </CONSEQUENCE> <PURPOSE><current/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#user.name"/> <DATA ref="#user.home-info.postal"/> <DATA ref="#user.home-info.telecom.telephone"/> <DATA ref="#user.business-info.postal"/> <DATA ref="#user.business-info.telecom.telephone"/> <DATA ref="#user.home-info.online.email"/> <DATA ref="#user.login.id"/> <DATA ref="#user.login.password"/> <DATA ref="#dynamic.miscdata"> <CATEGORIES><purchase/></CATEGORIES> </DATA> </DATA-GROUP> </STATEMENT> <STATEMENT> <CONSEQUENCE> At your request, we will send you carefully selected marketing solicitations that we think you will be interested in. </CONSEQUENCE> <PURPOSE> <contact required="opt-in"/> <individual-decision required="opt-in"/> <tailoring required="opt-in"/> </PURPOSE> <RECIPIENT><ours/><same required="opt-in"/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#user.name" optional="yes"/> <DATA ref="#user.home-info.postal" optional="yes"/> <DATA ref="#user.home-info.telecom.telephone" optional="yes"/> <DATA ref="#user.business-info.postal" optional="yes"/> <DATA ref="#user.business-info.telecom.telephone" optional="yes"/> <DATA ref="#user.home-info.online.email" optional="yes"/> </DATA-GROUP> </STATEMENT> <STATEMENT> <CONSEQUENCE> We allow you to set a password so that you can access your own information. </CONSEQUENCE> <PURPOSE><individual-decision required="opt-in"/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#user.login.id"/> <DATA ref="#user.login.password"/> <CATEGORIES><uniqueid/></CATEGORIES> </DATA> </DATA-GROUP> </STATEMENT> <STATEMENT> <CONSEQUENCE> At your request, we will tailor our site and highlight products related to your interests. </CONSEQUENCE> <PURPOSE> <pseudo-decision required="opt-in"/> <tailoring required="opt-in"/> </PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#user.bdate.ymd.year" optional="yes"/> <DATA ref="#user.gender" optional="yes"/> </DATA-GROUP> </STATEMENT> <STATEMENT> <CONSEQUENCE> We tailor our site based on your past visits. </CONSEQUENCE> <PURPOSE><tailoring/><develop/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#dynamic.cookies"> <CATEGORIES><state/></CATEGORIES> </DATA> <DATA ref="#dynamic.miscdata"> <CATEGORIES><preference/></CATEGORIES> </DATA> </DATA-GROUP> </STATEMENT> </POLICY> </POLICIES>
This section defines the syntax and semantics of P3P policies. All policies MUST be encoded using [UTF-8].
In cases where the P3P vocabulary is not precise enough to describe a Web
site's practices, sites should use the vocabulary terms that most closely
match their practices and provide further explanation in the
CONSEQUENCE
field and/or their human-readable policy. However,
policies MUST NOT make false or misleading statements.
Policies have to be placed inside a POLICIES
element.
POLICIES
elementThe POLICIES
element gathers one or more�P3P policies together
in a single file. This is provided as a performance optimization: many
policies can be collected with a single request, improving network traffic and
caching.
A POLICIES
element is the root element of policy files.
Further, the POLICIES
element can be put within the policy
reference file, inside the META
element:: in this case, user
agents need only fetch a single file, containing both the policy reference
file and the policies.
The POLICIES
element can optionally contain an
xml:lang
attribute (see section 2.4.2),
an EXPIRY
element, indicating
the expiration of the included policies, and an embedded data schema using the
DATASCHEMA
element (see Section 5).
Since policies are included in a POLICIES
element, each MUST
have a name
attribute which is unique in the file. This allows
policy references (in POLICY-REF
elements) to link to that
policy.
Example 3.3:
The file in http://www.example.com/Shop/policies.xml
could
have the following content:
<POLICIES xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY name="policy1" discuri="http://www.example.com/disc1"> .... </POLICY> <POLICY name="policy2" discuri="http://www.example.com/disc2"> .... </POLICY> <POLICY name="policy3" discuri="http://www.example.com/disc3"> .... </POLICY> </POLICIES>
The files in http://www.example.com/Shop/CDs/*
could then be
associated to the second policy ("policy2
") using the following
policy reference file in http://www.example.com/w3c/p3p.xml
:
<META xmlns="http://www.w3.org/2002/01/P3Pv1"> <POLICY-REFERENCES> ��� <POLICY-REF about="/Shop/policies#policy2"> ����� <INCLUDE>/Shops/CDs/*</INCLUDE> ��� </POLICY-REF> </POLICY-REFERENCES> </META>
| [19] | policies |
= |
`<POLICIES xmlns="http://www.w3.org/2002/01/P3Pv1"` [xml-lang] `>` [expiry] [dataschema] *policy "</POLICIES>" |
POLICY
elementThe POLICY
element contains a complete P3P policy. Each P3P
policy MUST contain exactly one POLICY
element. The policy
element MUST contain an ENTITY
element that identifies the legal
entity making the representation of the privacy practices contained in the
policy. In addition, the policy element MUST contain an ACCESS
element, one or more STATEMENT
elements, a
DISPUTES-GROUP
element, a P3P data
schema, and one or more extensions.
<POLICY>
name
(mandatory
attribute)discuri
(mandatory
attribute)opturi
purpose
with required
attribute set to opt-in
or opt-out
. Note that
the opt-in or opt-out procedures are determined by each site and may not
necessarily include a central mechanism for the entire site or an
automated online mechanism.xml:lang
| [20] | policy |
= |
`<POLICY name=` quotedstring ` discuri=` quoted-URI [` opturi=` quoted-URI] [xml-lang] `>` *extension [test] entity access [disputes-group] 1*statement-block *extension `</POLICY>` |
| [21] | quoted-URI |
= |
`"` URI `"` |
| Here, URI is defined as per RFC 2396 [URI]. |
TEST
elementThe TEST element is used for testing purposes: the presence of
TEST
in a policy indicates that the policy is just an example,
and as such, it MUST be ignored, and not be considered as a valid P3P
policy.
| [22] | test |
= |
"<TEST/>" |
ENTITY
elementThe ENTITY
element gives a precise description of the legal
entity making the representation of the privacy practices.
<ENTITY>
The ENTITY
element contains a description of the legal entity
consisting of DATA elements referencing (all or some of)
the fields of the business dataset: it MUST
contain both the legal entity's name and one or more contact information
fields among postal address, telephone number, email address, URI. Note that
some laws and codes of conduct require entities to include a postal address or
other specific information in their contact information.
| [23] | entity |
= |
"<ENTITY>" *extension entitydescription *extension "</ENTITY>" |
| [24] | entitydescription |
= |
"<DATA-GROUP>" `<DATA ref="#business.name"/>` PCDATA "</DATA>" *(`<DATA ref="#business.` string `"/>` PCDATA "</DATA>") "</DATA-GROUP>" |
Here, string is defined as a
sequence of characters (with " and & escaped) among the values
that are allowed by the business dataset.
PCDATA is defined as in [XML]. |
ACCESS
elementThe ACCESS
element indicates whether the site provides access
to various kinds of information.
<ACCESS>
<all/>
) is not
meant to imply that access to all data is possible, but that some of the
data may be accessible and that the user should communicate further with
the service provider to determine what capabilities they have.
Note that service providers may also wish to provide capabilities to access information collected through means other than the Web at the discuri. However, the scope of P3P statements are limited to data collected through HTTP or other Web transport protocols. Also, if access is provided through the Web, use of strong authentication and security mechanisms for such access is recommended; however, security issues are outside the scope of this document.
The ACCESS
element must contain one of the following
elements:
<nonident/>
<all/>
<contact-and-other/>
<ident-contact/>
<other-ident/>
<none/>
| [25] | access |
= |
"<ACCESS>" *extension access_disclosure *extension "</ACCESS>" |
| [26] | access_disclosure |
= |
"<nonident/>" | ; Identified Data is Not Used |
DISPUTES
elementA policy SHOULD contain a DISPUTES-GROUP
element, which
contains one or more DISPUTES
elements. These elements describe
dispute resolution procedures that may be followed for disputes about a
services' privacy practices. Each DISPUTES
element can optionally
contain a LONG-DESCRIPTION
element, an IMG
element,
and a REMEDIES
element. Service providers with multiple dispute
resolution procedures should use a separate DISPUTES
element for
each. Since different dispute procedures have separate remedy processes, each
DISPUTES
element would need a separate
LONG-DESCRIPTION
, IMG
tag and REMEDIES
element, if they are being used.
<DISPUTES>
resolution-type
(mandatory
attribute)[service]
[independent]
[court]
[law]
service
(mandatory
attribute)verification
short-description
The DISPUTES
element can contain a
LONG-DESCRIPTION
element, where a human readable description is
present: this should contain the name of the appropriate legal forum,
applicable law, or third party organization; or contact information for
customer service if not already provided at the service URI.
<LONG-DESCRIPTION>
<IMG>
src
(mandatory
attribute)width
height
alt
(mandatory attribute)| [27] | disputes-group |
= |
"<DISPUTES-GROUP>" *extension 1*dispute *extension "</DISPUTES-GROUP>" |
| [28] | dispute |
= |
"<DISPUTES" " resolution-type=" '"'("service"|"independent"|"court"|"law")'"' �" service=" quoted-URI [" verification=" quotedstring] [" short-description=" quotedstring] ">" *extension [longdescription] [image] [remedies] *extension "</DISPUTES>" |
| [29] | longdescription |
= |
<LONG-DESCRIPTION> PCDATA </LONG-DESCRIPTION> |
| [30] | image |
= |
"<IMG src=" quoted-URI [" width=" `"` number `"`] [" height=" `"` number `"`] " alt=" quotedstring "/>" |
| [31] | quotedstring |
= |
`"` string `"` |
Here, string is defined as a
sequence of characters (with " and & escaped), and
PCDATA is defined as in [XML]. |
Note that there can be multiple assurance services, specified via multiple
occurrences of DISPUTES
within the DISPUTES-GROUP
element. These fields are expected to be used in a number of ways, including
representing that one's privacy practices are self assured, audited by a third
party, or under the jurisdiction of a regulatory authority.
REMEDIES
elementEach DISPUTES
element SHOULD contain a REMEDIES
element that specifies the possible remedies in case a policy breach
occurs.
<REMEDIES>
The REMEDIES
element must contain one or more of the
following:
<correct/>
<money/>
<law/>
| [32] | remedies |
= |
"<REMEDIES>" *extension 1*remedy *extension "</REMEDIES>" |
| [33] | remedy |
= |
"<correct/>" | "<money/>" | "<law/>" |
Statements describe data practices that are applied to particular types of data.
STATEMENT
elementThe STATEMENT
element is a container that groups together a
PURPOSE
element, a RECIPIENT
element, a
RETENTION
element, a DATA-GROUP
element, and
optionally a CONSEQUENCE
element and one or more extensions. All
of the data referenced by the DATA-GROUP
is handled according to
the disclosures made in the other elements contained by the statement. Thus,
sites may group elements that are handled the same way and create a statement
for each group. Sites that would prefer to disclose separate purposes and
other information for each kind of data they collect can do so by creating a
separate statement for each data element.
<STATEMENT>
| [34] | statement-block |
= |
"<STATEMENT>" *extension [consequence] ((purpose recipient retention 1*data-group) | (non-identifiable [purpose] [recipient] [retention] *data-group)) *extension "</STATEMENT>" |
To simplify practice declaration, service providers may aggregate any of
the disclosures (purposes, recipients, and retention) within a statement over
data elements. Service providers MUST make such aggregations as an additive
operation. For instance, a site that distributes your age to ours
(ourselves and our agents), but distributes your postal code to
unrelated
(unrelated third parties), MAY say they distribute your
name and postal code to ours
and unrelated
. Such a
statement appears to distribute more data than actually happens. It is up to
the service provider to determine if their disclosure deserves specificity or
brevity. Note that when aggregating disclosures across statements that include
the NON-IDENTIFIABLE
element, this element may be included in the
aggregated statement only if it would otherwise appear in every statement if
the statements were written separately.
Also, one must always disclose all options that apply. Consider a site with
the sole purpose of collecting information for the purposes of
contact
(Contacting Visitors for Marketing of Services or
Products). Even though this is considered to be for the current
(Completion and Support of Activity For Which Data Was Provided) purpose, the
site must state both contact
and current
purposes.
Consider a site which distributes information to ours
in order to
redistribute it to public
: the site must state both
ours
and public
recipients.
Service providers often aggregate data they collect. Sometimes this aggregate data may be used for different purposes than the original data, shared more widely than the original data, or retained longer than the original data. For example many sites�publish or disclose to their advertisers statistics such as number of visitors to their Web site, percentage of visitors who fit into various demographic groups, etc. When �aggregate statistics are used or shared such that it would not be possible to derive data for individual people or households based on these statistics, no disclosures about these statistics are necessary in a P3P policy. However, services MUST disclose the fact that the original data is collected and declare any use that is made of the data before it is aggregated.
CONSEQUENCE
elementSTATEMENT
elements may optionally contain a
CONSEQUENCE
element that can be shown to a human user to provide
further explanation about a site's practices.
<CONSEQUENCE>
| [35] | consequence |
= |
"<CONSEQUENCE>" PCDATA "</CONSEQUENCE>" |
NON-IDENTIFIABLE
elementA STATEMENT
element may optionally contain the
NON-IDENTIFIABLE
element, signifying either that there is no data
collected under this STATEMENT
, or that all of the data
referenced by that STATEMENT
will be anonymized upon
collection.
<NON-IDENTIFIABLE/>
STATEMENT
. In order to
consider the data "anonymized", there must be no reasonable way for the
entity or a third party to attach the collected data to the identity of
a natural person. Some types of data are inherently anonymous, such as
randomly-generated session IDs. Data which might identify natural people
in some circumstances, such as IP addresses, names, or addresses, must
have a non-reversible transformation applied in order be considered
"anonymized".If the NON-IDENTIFIABLE
element is present in any
STATEMENT
elements in a policy, then a human readable explanation
of how the data is anonymized MUST be included or linked to at the discuri .
Also, if the NON-IDENTIFIABLE
element is present in a
STATEMENT
then the other elements in that STATEMENT
are optional.
| [36] | non-identifiable |
= |
"<NON-IDENTIFIABLE/>" |
PURPOSE
elementEach STATEMENT
element �that does not include a
NON-IDENTIFIABLE
element MUST contain a PURPOSE
element that contains one or more purposes of data collection or uses of data.
Sites MUST classify their data practices into one or more of the purposes
specified below.
<PURPOSE>
The PURPOSE
element MUST contain one or more of the
following:
<current/>
<admin/>
<develop/>
<tailoring/>
<pseudo-analysis/>
<pseudo-decision/>
<individual-analysis/>
<individual-decision/>
<contact/>
<current/>
would be
used. In addition, this does not include marketing via customized Web
content or banner advertisements embedded in sites the user is visiting
-- these cases would be covered by the
<tailoring/>
,
<pseudo-analysis/>
and
<pseudo-decision/>
, or
<individual-analysis/>
and
<individual-decision/>
�purposes.<historical/>
<DISPUTES>
element and MUST include a specific
definition of the type of qualified researcher who can access the
information, where this information will be stored and specifically how
this collection advances the preservation of history.<telemarketing/>
<current/>
would be used.<other-purpose>
string
</other-purpose>
Each type of purpose (with the exception of current
) can have
the following optional attribute:
required
always
: The purpose is always
required; users cannot opt-in or opt-out of this use of their data.
This is the default when no required
attribute is
present.opt-in
: Data may be used for this
purpose only when the user affirmatively requests this use -- for
example, when a user asks to be added to a mailing list. An
affirmative request requires users to take some action specifically
to make the request. For example, when users fill out a survey,
checking an additional box to request to be added to a mailing list
would be considered an affirmative request. However, submitting a
survey form that contains a pre-checked mailing list request box
would not be considered an affirmative request. In addition, for any
purpose that users may affirmatively request, there must also be a
way for them to change their minds later and decline -- this MUST be
specified at the opturi
.opt-out
: Data may be used for this
purpose unless the user requests that it not be used in this way.
When this value is selected, the service MUST provide clear
instructions to users on how to opt-out of this purpose at the
opturi
. Services SHOULD also
provide these instructions or a pointer to these instructions at the
point of data collection.| [37] | purpose |
= |
"<PURPOSE>" *extension 1*purposevalue *extension "</PURPOSE>" |
| [38] | purposevalue |
= |
"<current/>" | ; Completion and Support of Activity For Which Data Was Provided "<admin" [required] "/>" | ; Web Site and System Administration "<develop" [required] "/>" | ; Research and Development "<tailoring" [required] "/>" | ; One-time Tailoring "<pseudo-analysis" [required] "/>" | ; Pseudonymous Analysis "<pseudo-decision" [required] "/>" | ; Pseudonymous Decision "<individual-analysis" [required] "/>" | ; Individual Analysis "<individual-decision" [required] "/>" | ; Individual Decision "<contact" [required] "/>" | ; Contacting Visitors for Marketing of Services or Products "<historical" [required] "/>" | ; Historical Preservation "<telemarketing" [required] "/>" | ; Telephone Marketing "<other-purpose" [required] ">" PCDATA "</other-purpose>"; Other Uses |
| [39] | required |
= |
" required=" `"` ("always"|"opt-in"|"opt-out") `"` |
Service providers MUST use the above elements to explain the purpose of
data collection. Service providers MUST disclose all that apply. If a
service provider does not disclose that a data element will be used for a
given purpose, that is a representation that data will not be used for that
purpose. Service providers that disclose that they use data for
"other
" purposes MUST provide human readable explanations of
those purposes.
RECIPIENT
elementEach STATEMENT
element that does not include a
NON-IDENTIFIABLE
element MUST contain a RECIPIENT
element that contains one or more recipients of the collected data. Sites MUST
classify their recipients into one or more of the six recipients
specified.
<RECIPIENT>
The RECIPIENT
element MUST contain one or more of the
following:
<ours>
<delivery>
<same>
<other-recipient>
<unrelated>
<public>
Each of the above tags can optionally contain:
recipient-description
tags, containing a
description of the recipient;<ours>
, a required
attribute: this attribute is defined
exactly as the analogous attribute in the�PURPOSE
tag,
indicating whether opt-in/opt-out of sharing is available (and, its
default value is always
).| [40] | recipient |
= |
"<RECIPIENT>" *extension 1*recipientvalue *extension "</RECIPIENT>" |
| [41] | recipientvalue |
= |
"<ours>" *recdescr "</ours> | ; only ourselves and our agents "<same" [required] ">" *recdescr "</same>" | ; legal entities following our practices "<other-recipient" [required] ">" *recdescr "</other-recipient>" | ; legal entities following different practices "<delivery" [required] ">" *recdescr "</delivery>" | ; delivery services following different practices "<public" [required] ">" *recdescr "</public>" | ; public fora "<unrelated" [required] ">" *recdescr "</unrelated>" ; unrelated third parties |
| [42] | recdescr |
= |
"<recipient-description>" PCDATA ; description of the recipient "</recipient-description>" |
Service providers MUST disclose all the recipients that apply. P3P makes no distinctions about how that data is released to the recipient; it simply requires that if data is released, then that sharing must be disclosed in the P3P policy. Examples of disclosing data which MUST be covered by a P3P statement include:
Note that in some cases the above set of recipients may not completely describe all the recipients of data. For example, the issue of transaction facilitators, such as shipping or payment processors, who are necessary for the completion and support of the activity but may follow different practices was problematic. Currently, only delivery services can be explicitly represented in a policy. Other such transaction facilitators should be represented in whichever category most accurately reflects their practices with respect to the original service provider.
A special element for delivery services is included, but not one for payment processors (such as banks or credit card companies) for the following reasons: Financial institutions will typically have separate agreements with their customers regarding the use of their financial data, while delivery recipients typically do not have an opportunity to review a delivery service's privacy policy.
Note that the <delivery/>
element SHOULD NOT be used for
delivery services that agree to use data only on behalf of the service
provider for completion of the delivery.
RETENTION
elementEach STATEMENT
element that does not include a
NON-IDENTIFIABLE
element MUST contain a RETENTION
element that indicates the kind of retention policy that applies to the data
referenced in that statement.
<RETENTION>
The RETENTION
element MUST contain one of the following:
<no-retention/>
<stated-purpose/>
<legal-requirement/>
<business-practices/>
<indefinitely/>
| [43] | retention |
= |
"<RETENTION>" *extension retentionvalue *extension "</RETENTION>" |
| [44] | retentionvalue |
=� |
"<no-retention/>" | ; not retained "<stated-purpose/>" | ; for the stated purpose "<legal-requirement/>" | ; stated purpose by law "<indefinitely/>" | ; indeterminate period of time "<business-practices/>" ; by business practices |
DATA-GROUP
and
DATA
elementsEach STATEMENT
element that does not include a
NON-IDENTIFIABLE
element MUST contain at least one
DATA-GROUP
element that contains one or more DATA
elements. DATA
elements are used to describe the type of data
that a site collects.
<DATA-GROUP>
base
ref
attributes. When this attribute is omitted,
the default value is the URI of the P3P base data schema (http://www.w3.org/TR/P3P/base).
When the attribute appears as an empty string (""), the base is the
local document.<DATA>
ref
(mandatory attribute)DATA
element is contained
within a DATA-GROUP
element, then the default base URI is
assumed to be the URI of the base
attribute. In the other
cases, as usual, the default base URI is a same-document reference ([URI]).user.gender
is different from USER.GENDER
or
User.Gender
).optional
optional
attribute is used only in policies
(not in data schema definitions).Note that user agents should be cautious about using the
optional
attribute in automated decision-making. If the
optional
attribute is associated with a data element directly
controlled by the user agent (such as the HTTP Referer
header or
cookies), the user agent should make sure that this data is not transmitted to
Web sites at which a data element is optional if the site's policy would not
match a user's preferences if the data element was required. Likewise, for
data elements that users typically type into forms, �user agents should alert
users when a site's practices about optional data do not match their
preferences.
DATA
elements can contain the actual data (as already sen in
the case of the ENTITY
element), and can contain related category information.
| [45]� | data-group |
= |
"<DATA-GROUP" [" base=" quoted-URI] ">" *extension 1*dataref *extension "</DATA-GROUP>" |
| [46] | dataref |
= |
`<DATA" ref="` URI-reference `"` [" optional=" `"` ("yes"|"no") `"`] ">" [categories] ; the categories of the data element. [PCDATA] ; the eventual value of the data element "</DATA>" |
Here, URI-reference is defined
as in [URI]. |
For example, to reference the user's home address city, all the elements of
the data set user.business-info
and (optionally) all the elements
of the data set user.home-info.telecom
, the service would send
the following references inside a P3P policy:
<DATA-GROUP> <DATA ref="#user.home-info.city"/> <DATA ref="#user.home-info.telecom" optional="yes"/> <DATA ref="#user.business-info"/> </DATA-GROUP>
When the actual value of the data is known, it can be expressed inside the
DATA
element. For example, as seen in the example policies:
<ENTITY> <DATA-GROUP> <DATA ref="#business.name">CatalogExample</DATA> <DATA ref="#business.contact-info.postal.street">4000 Lincoln Ave.</DATA> ...
CATEGORIES
elementCategories are elements inside data elements that provide hints to users
and user agents as to the intended uses of the data. Categories are vital to
making P3P user agents easier to implement and use. Note that categories
are not data elements: they just allow users to express more generalized
preferences and rules over the exchange of their data. Categories SHOULD NOT
be used within the DATA
elements of an ENTITY
element.
The following elements are used to denote data categories:
| [47] | categories |
= |
"<CATEGORIES>" 1*category "</CATEGORIES>" |
| [48] | category |
= |
"<physical/>" | ; Physical Contact Information "<online/>" | ; Online Contact Information "<uniqueid/>" | ; Unique Identifiers "<purchase/>" | ; Purchase Information "<financial/>" | ; Financial Information "<computer/>" | ; Computer Information "<navigation/>" | ; Navigation and Click-stream Data "<interactive/>" | ; Interactive Data "<demographic/>" | ; Demographic and Socioeconomic Data "<content/>" | ; Content "<state/>" | ; State Management Mechanisms "<political/>" | ; Political Information "<health/>" | ; Health Information "<preference/>" | ; Preference Data "<location/>" | ; Location Data "<government/> | ; Government-issued Identifiers "<other-category>" PCDATA "</other-category>" ; Other |
<physical/>
<online/>
<uniqueid/>
<purchase/>
<financial/>
<computer/>
<navigation/>
<interactive/>
<demographic/>
<content/>
<state/>
<political/>
<health/>
<preference/>
<location/>
<government/>
<other-category>
string
</other-category>
<other-category>
and the
</other-category>
tags.)The Computer, Navigation, Interactive and Content categories can be distinguished as follows. The Computer category includes information about the user's computer including IP address and software configuration. Navigation data describes actual user behavior related to browsing. When an IP address is stored in a log file with information related to browsing activity, both the Computer category and the Navigation category should be used. Interactive Data is data actively solicited to provide some useful service at a site beyond browsing. Content is information exchanged on a site for the purposes of communication.
The Other category should be used only when data is requested that does not fit into any other category.
P3P uses categories to give users and user agents additional hints as to what type of information is requested from a service. While most data in the base data schema is in a known category (or a set of known categories), some data elements can be in a number of different categories, depending on the situation. The former are called fixed-category data elements (or "fixed data elements" for short), the latter variable-category data elements ("variable data elements"). Both types of elements are described in Section 5.7.
EXTENSION
elementP3P provides a flexible and powerful mechanism to extend its syntax and
semantics using one element: EXTENSION
. This element is used to
indicate portions of the policy/policy reference file/data schema which belong
to an extension. The meaning of the data within the EXTENSION
element is defined by the extension itself.
<EXTENSION>
optional
optional
attribute a value of no
. A
mandatory extension to the P3P syntax means that applications
that do not understand this extension cannot understand the meaning of
the whole policy (or policy reference file, or data schema) containing
it. An optional extension, indicated by giving the optional
attribute a value of yes
, means that applications that do
not understand this extension can safely ignore the contents of the
EXTENSION
element, and proceed to process the whole policy
(or policy reference file, or data schema) as usual. The
optional
attribute is not required; its default value is
yes
.| [49] | extension |
= |
"<EXTENSION" [" optional=" `"` ("yes"|"no") `"`] ">" PCDATA "</EXTENSION>" |
For example, if www.catalog.example.com would like to add to P3P a feature to indicate that a certain set of data elements were only to be collected from users living in the United States, Canada, or Mexico, it could add a mandatory extension like this:
<DATA-GROUP> ... <EXTENSION optional="no"> <COLLECTION-GEOGRAPHY type="include" xmlns="http://www.catalog.example.com/P3P/region"> <USA/><Canada/><Mexico/> </COLLECTION-GEOGRAPHY> </EXTENSION> </DATA-GROUP>
On the other hand, if www.catalog.example.com would like to add an extension stating what country the server is in, an optional extension might be more appropriate, such as the following:
<POLICY> <EXTENSION optional="yes"> <ORIGIN xmlns="http://www.catalog.example.com/P3P/origin" country="USA"/> </EXTENSION> ... </POLICY>
The xmlns
attribute is significant since it specifies the
namespace for interpreting the names of elements and attributes used in the
extension. Note that, as specified in [XML-Name], the
namespace URI is just intended to be a unique identifier for the XML entities
used by the extension. Nevertheless, service providers MAY provide a page with
a description of the extension at the corresponding URI.
The EXTENSION
element can appear in various places within P3P
syntax: such positions are normatively specified by the XML Schema present in
Appendix 4 (and, informally specified by the
ABNF syntax, and by the DTD present in Appendix 5)..
User agents MUST document a method by which preferences can be imported and processed, and SHOULD document a method by which preferences can be exported.
P3P user agents MUST act according to the preference settings selected by the user. This requires that they be able to process policy and policy reference files as appropriate to evaluate each policy with respect to a user's preferences or other criteria specified by the settings. Depending on these settings, this may require, for example, that the user agent verify that required parts of the P3P policy are present, or check that the syntax of the entire policy is valid.
Compact policies are summarized P3P policies that provide hints to user agents to enable the user agent to make quick, synchronous decisions about applying policy. Compact policies are a performance optimization that is OPTIONAL for either user agents or servers. User agents that are unable to obtain enough information from a compact policy to make a decision according to a user's preferences SHOULD fetch the full policy.
In P3P, compact policies contain policy information related to cookies (cf. [COOKIES] and [STATE]) only. The Web server is responsible for building a P3P compact policy to represent the cookies referenced in a full policy. The policy specified in a P3P compact policy applies to data stored within all cookies set in the same HTTP response as the compact policy, all cookies set by scripts associated with that HTTP response, and also to data linked to the cookies.
Any HTTP resource MAY include a P3P compact policy through the P3P response
header (cf. Section 2.2.2). If a site is using P3P
headers, it SHOULD include this on responses for all appropriate request
methods, including HEAD
and OPTION
requests.
The P3P compact policy header has a quoted string that may contain one or more delimited tokens (the "compact policy"). Tokens can appear in any order, and the space character (" ") is the only valid delimiter. The syntax for this header is as follows:
| [50] | compact-policy-field |
= |
`CP="` compact-policy `"` |
| [51] | compact-policy |
= |
compact-token *(" " compact-token) |
| [52] | compact-token |
= |
compact-access | compact-disputes | compact-remedies | compact-non-identifiable | compact-purpose | compact-recipient | compact-retention | compact-categories | compact-test |
As for all HTTP headers, the name of the P3P header field is case-insensitive. The field-value (i.e., the content of the header) is instead case sensitive.
If an HTTP response includes more than one compact policy, P3P user agents MUST ignore all compact policies after the first one.
P3P compact policies use tokens representing the following elements from
the P3P vocabulary: ACCESS
, CATEGORIES
,
DISPUTES
, NON-INDENTIFIABLE
, PURPOSE
,
RECIPIENT
, REMEDIES
, RETENTION
,
TEST
.
If a token appears more than once in a single compact policy, the compact policy has the same semantics as if that token appeared only once. If an unrecognized token appears in a compact policy, the compact policy has the same semantics as if that token was not present.
The P3P compact policy vocabulary is expressed using a developer-readable language to reduce the number of bytes transferred over the wire within a HTTP response header. The syntax of the tokens follows:
ACCESS
Information in the ACCESS
element is represented in compact
policies using tokens composed by a three letter code:
| [53] | compact-access |
= |
"NOI" | ; for <nonident/> "ALL" | ; for <all/> "CAO" | ; for <contact-and-other/> "IDC" | ; for <ident-contact/> "OTI" | ; for <other-ident/> "NON" ; for <none/> |
DISPUTES
If a full P3P policy contains a DISPUTES-GROUP
element that
contains one or more DISPUTES
elements, then the server should
signal the user agent by providing a single
"DSP
" token in the P3P-compact policy field:
| [54] | compact-disputes |
= |
"DSP" ; there are some DISPUTES |
REMEDIES
Information in the REMEDIES
element is represented in compact
policies as follows:
| [55] | compact-remedies |
= |
"COR" | ; for <correct/> "MON" | ; for <money/> "LAW" ; for <law/> |
NON-IDENTIFIABLE
The presence of the NON-IDENTIFIABLE
element in every
statement of the policy is signaled by the NID
token (note that
the NID
token MUST NOT be used unless the
NON-IDENTIFIABLE
element is present in every statement within the
policy):
| [56] | compact-non-identifiable |
= |
"NID" ; for <NON-IDENTIFIABLE/> |
PURPOSE
Purposes are expressed in P3P compact policy format using tokens composed
by a three letter code plus an optional one letter attribute. Such an optional
attribute encodes the value of the "required
" attribute in full
P3P policies: its value can be "a
", "i
" and
"o
", which mean that the "required
" attribute in the
corresponding P3P policy must be set to "always
",
"opt-in
" and "opt-out
" respectively.
If a P3P compact policy needs to specify one or more other-purposes in its
full P3P policy, a single OTP
flag is used to signal the user
agent that other-purposes exist in the full P3P policy.
The corresponding associations among P3P purposes and compact policy codes follow:
| [57] | compact-purpose |
= |
"CUR" | ; for <current/> "ADM" [creq] | ; for <admin/> "DEV" [creq] | ; for <develop/> "TAI" [creq] | ; for <tailoring/> "PSA" [creq] | ; for <pseudo-analysis/> "PSD" [creq] | ; for <pseudo-decision/> "IVA" [creq] | ; for <individual-analysis/> "IVD" [creq] | ; for <individual-decision/> "CON" [creq] | ; for <contact/> "HIS" [creq] | ; for <historical/> "TEL" [creq] | ; for <telemarketing/> "OTP" [creq] ; for <other-purpose/> |
| [58] | creq |
= |
"a"| ;"always" "i"| ;"opt-in" "o" ;"opt-out" |
RECIPIENT
Recipients are expressed in P3P compact policy format using a three letter
code plus an optional one letter attribute. Such an optional attribute encodes
the value of the "required
" attribute in full P3P policies: its
value can be "a
", "i
" and "o
", which
mean that the "required
" attribute in the corresponding P3P
policy must be set to "always
", "opt-in
" and
"opt-out
" respectively.
The corresponding associations among P3P recipients and compact policy codes follow:
| [59] | compact-recipient |
= |
"OUR" | ; for <ours/> "DEL" [creq] | ; for <delivery/> "SAM" [creq] | ; for <same/> "UNR" [creq] | ; for <unrelated/> "PUB" [creq] | ; for <public/> "OTR" [creq] ; for <other-recipient/> |
RETENTION
Information in the RETENTION
element is represented in compact
policies as follows:
| [60] | compact-retention |
= |
"NOR" | ; for <no-retention/> "STP" | ; for <stated-purpose/> "LEG" | ; for <legal-requirement/> "BUS" | ; for <business-practices/> "IND" ; for <indefinitely/> |
CATEGORIES
Categories are represented in compact policies as follows:
| [61] | compact-categories |
= |
"PHY" | ; for <physical/> "ONL" | ; for <online/> "UNI" | ; for <uniqueid/> "PUR" | ; for <purchase/> "FIN" | ; for <financial/> "COM" | ; for <computer/> "NAV" | ; for <navigation/> "INT" | ; for <interactive/> "DEM" | ; for <demographic/> "CNT" | ; for <content/> "STA" | ; for <state/> "POL" | ; for <political/> "HEA" | ; for <health/> "PRE" | ; for <preference/> "LOC" | ; for <location/> "GOV" | ; for <government/> "OTC" ; for <other-category/> |
Note that if a P3P policy specifies one or more other-category
in its full P3P policy, a single OTC
token is
used to signal the user agent that other-category
's exist in the
full P3P policy.
TEST
The presence of the TEST
element is signaled by the
TST
token:
| [62] | compact-test |
= |
"TST" ; for <TEST/> |
When a P3P compact policy is included in a HTTP response header, it applies
to cookies set by the current response. This includes cookies set through the
use of a HTTP SET-COOKIE
header or cookies set by script.
To use compact policies, the validity of the full P3P policy must span the lifetime of the cookie. There is no method to indicate that policy is valid beyond the life of the cookie because the value of user agent caching is marginal, since sites would not know when to optimize by not sending the compact policy. When a server sends a compact policy, it is asserting that the compact policy and corresponding full P3P policy will be in effect for at least the lifetime of the cookie to which it applies.
When using P3P compact policies, the Web site is responsible for building a
compact policy by summarizing the policy referenced by the
COOKIE-INCLUDE
elements of a P3P policy reference file. If a
site's policy reference file uses COOKIE-EXCLUDE
elements then
the site will need to manage sending the correct P3P compact policies to the
user agent given the cookies set in a specific response.
The transformation of a P3P policy to a P3P compact policy may result in a loss of descriptive policy information -- the compact policy may not contain all of the policy information specified in the full P3P policy. The information from the full policy that is discarded when building a compact policy includes expiry, data group/data-schema elements, entity elements, consequences elements, and disputes elements are reduced.
Full policies that include mandatory extensions MUST NOT be represented as compact policies.
All of the purposes, recipients, and categories that appear in multiple statements in a full policy MUST be aggregated in a compact policy, as described in section 3.3.1. When performing the aggregation, a Web site MUST disclose all relevant tokens (for instance, observe Example 4.1, where multiple retention policies are specified.)
In addition, for each fixed category data element appearing in a statement the associated category as defined in the associated schema MUST be included in the compact policy.
Example �4.1:
Consider the following P3P policy:
<POLICY name="sample" discuri="http://www.example.com/cookiepolicy.html" opturi="http://www.example.com/opt.html"> <ENTITY> <DATA-GROUP> <DATA ref="#business.name">Example, Corp.</DATA> <DATA<EMAIL_ADDRESS></DATA-GROUP> </ENTITY> <ACCESS><none/></ACCESS> <DISPUTES-GROUP> <DISPUTES resolution-type="service" service="http://www.example.com/privacy.html" short-description="Please contact our customer service desk with privacy concerns by emailing<EMAIL_ADDRESS></DISPUTES-GROUP> <STATEMENT> <PURPOSE><admin/><develop/><pseudo-decision/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><indefinitely/></RETENTION> <DATA-GROUP> <DATA ref="#dynamic.cookies"> <CATEGORIES><preference/><navigation/></CATEGORIES> </DATA> </DATA-GROUP> </STATEMENT> <STATEMENT> <PURPOSE><individual-decision required="opt-out"/></PURPOSE> <RECIPIENT><ours/></RECIPIENT> <RETENTION><stated-purpose/></RETENTION> <DATA-GROUP> <DATA ref="#user.name.given"/> <DATA ref="#dynamic.cookies"> <CATEGORIES><preference/><uniqueid/></CATEGORIES> </DATA> </DATA-GROUP> </STATEMENT> </POLICY>
The corresponding compact policy is:
"NON DSP ADM DEV PSD IVDo OUR IND STP PHY PRE NAV UNI"
Some user agents may attempt to generate a full P3P policy from a compact
policy, for use in evaluating user preferences. They will not be able to
provide values for the ENTITY
and DISPUTES
elements
as well as a number of the attributes. However:
ACCESS
element, and: a single STATEMENT
element that contains the appropriate RECIPIENT
,
RETENTION
, and PURPOSE
elements, as well as a
dynamic.miscdata
element with
the appropriate CATEGORIES
.ACCESS
element, and: multiple STATEMENT
elements (as many as the different values of the compact retention) that
contain a different corresponding value for the RETENTION
element, the appropriate RECIPIENT
, and
PURPOSE
elements, as well as a dynamic.miscdata
element with the
appropriate CATEGORIES
.Note that, in agreement with the non ambiguity requirements stated in Section 2.4.1, a site MUST honor a compact policy for a given URI in any case (even when the full policy referenced in the policy reference file for that URI does not correspond, as per Section 4.5, to the compact policy itself).
A data schema is a description of a set of data. P3P includes a way to describe data schemas so that services can communicate to user agents about the data they collect. A data schema is built from a number of data elements, which are specific items of data a service might collect.
Data elements in a data schema can have the following properties:
<DATA>
element.
This is required on all data elements.Data elements are organized into a hierarchy. A data element automatically
includes all of the data elements below it in the hierarchy. For example, the
data element representing "the user's name" includes the data elements
representing "the user's given name", "the user's family name", and so on. The
hierarchy is based on the data element name. Thus the data elements
user.name.given, user.name.family,
and
user.name.nickname
are all children of the data element
user.name
, which is in turn a child of the data element
user
.
P3P has defined a data schema called the P3P base data schema that includes a large number of data elements commonly used by services.
Services may declare new data elements by creating and publishing their own
data schemas, which are created using the <DATASCHEMA>
element. Data schemas can either be published in standalone XML files (whose
root element is then DATASCHEMA
), or they can be embedded in a
policy file (even the same policy file with policies referencing the data
schema itself).
The <DATASCHEMA>
element is defined as follows:
| [63] | dataschema |
= |
"<DATASCHEMA" [` xmlns="http://www.w3.org/2002/01/P3Pv1"`] [xml-lang] ">" *(datadef|datastruct|extension) "</DATASCHEMA>" |
A standalone data schema has the <DATASCHEMA>
element as
the root element in the XML file. It must have the appropriate namespace
defined in the xmlns
attribute to identify it as a P3P data
schema, as follows:
<DATASCHEMA xmlns="http://www.w3.org/2002/01/P3Pv1"> <DATA-STRUCT ... /> ... <DATA-DEF ... /> </DATASCHEMA>
Optionally, DATASCHEMA
can contain an xml:lang
attribute (see section 2.4.2),
When a data schema is declared inside a policy file, then the
<DATASCHEMA>
element is still used (as described in Section 3.2.1, "The <POLICIES>
element").
Data schemas contain a number of fields in natural language. Services publishing a data schema MAY wish to translate these fields into multiple languages. The data element short and long names MAY be translated, but the data element name MUST NOT be translated - this field needs to stay constant across translations of a data schema.
If a service is going to provide a data schema in multiple natural
languages, then it SHOULD examine the Accept-Language
HTTP
request-header on requests for that data schema to pick the best available
alternative.