user doc: updated conditional mapping doc based on comments from Paul
@@ -9,9 +9,12 @@ processing to a mapping. For example, suppose that you are
mapping a source zip code field to a target zip code field.
If the source zip code field is empty, you might want to fill
the target field with `99999`. To do this, you would specify
-a Microsoft Excel expression that tests the zip code source
+an expression that tests the zip code source
field to determine if it is empty, and if it is empty,
inserts `99999` into the zip code target field.
+The data mapper supports expressions that are similar to a Microsoft
+Excel expressions, but does not support all Microsoft Excel expression
+syntax.
You can define zero or one condition for each mapping.
@@ -53,7 +56,7 @@ image:images/add-condition-to-mapping.png[Add expression] to
display the conditional expression input field.
+
In the expression field, the data mapper automatically displays
-the name of the source field in the current mapping.
+the names of the source fields in the current mapping.
. Specify a Microsoft Excel expression in the input field.
+
