837 Occurrence Fields

Jul 27, 2016 at 11:16 PM
I have 837 data and am generating PDFs. The parser is inserting my two occurrence code and date sets in field 31 a and then field 31 b. I expected it to put them in field 31 and 32, using the a line first. What is the reason for putting the second one in 31 b instead of 32 a?

Thanks for any help.