2.1.360 Part 1 Section 17.14.2, activeRecord (Record Currently Displayed In Merged Document)
a. The standard says that if the val attribute is greater than the number of records in the specified external data source, the val attribute is treated as if it were 1.
If the val attribute greater than the number of records in the specified external data source, Word fails to open the file.
b. The standard says that data is populated in merge fields based on mappings defined by the fieldMapData elements.
In Word, merge fields directly reference data columns in the data source, not fieldMapData mappings.