In the 837P Imp Guide (X098), the OTHER SUBSCRIBER NAME (NM1 in loop 2320A) segment shows usage as "Required." However, the note for this segment (which is also the beginning of the loop) states "...required when Loop ID-2320 - Other Subscriber Information is used. Otherwise, this loop is not used." So shouldn't the segment be marked as "Situational?"
I checked 004050X143 (November 2002, Review 2), and the change has not yet been made there.