MSIR.0337 After SIRFIELD (subcmd), alias (alias1) of field (field1) is no longer produced by PAI because alias (alias2) of related field (field2) now is
This informational message indicates that a SIRFIELD subcmd command was issued which caused a change in the behaviour of the PAI statement. Prior to this command, the name alias1 would be output by a PAI statement, but now it will not be. Instead, any occurrences of field1 will be hidden from PAI; only occurrences of the related field field2 are output from PAI, and they are output with alias2 as the name.
See the discussion of the PAI statement in the Sir2000 Field Migration Facility Reference Manual.