This command is used as part of the Document per Repeated Item (old style) feature.
When a separate document is required for each of a set of repeating items, but only where certain criteria apply to the item, then the «SetMultipleDocumentFilter» command can be used to filter the repeating items so as to achieve this.
For example, suppose there is a repeating data element Child and a separate letter is required for each child, but only where the child’s age is greater than 12. The SetMultipleDocumentFilter command will then be:
«SetMultipleDocumentFilter(Age > 12)»
Note that the scope of the Age data element is actually Child.
In order to compare the child’s Age with a minimum age somewhere at the root level of the data set, the following would be used:
«SetMultipleDocumentFilter(Age > ../MinimumAge)»
Repeating documents per item in a ForEach has been made far simpler, please refer to this post for more information.