'thread' element is optional.
@@ -64,7 +64,7 @@ PersistenceThreads = element persistence-threads {
attribute highest-priority-to-block { xsd:string } ? &
## Operations with priority better than this can block others
attribute lowest-priority-to-block-others { xsd:string } ? &
- Thread+
+ Thread*
}
MinNodeRatioPerGroup = element min-node-ratio-per-group {
