Check Printing remittance limit

I have written a check print output .rtf to print our checks on preprinted forms.   I have the remittance information on the top third, the check in the middle third, and the mailing info on the bottom third.   The remittance information can be 1-12 lines.   Any thing over that needs to print on another page (max 12 lines per page).   The default check .rtf has a 'VOID' area for overflow.   R11 documentation says the overflow will kick in at 37 remittance lines.   We are running under R12 and I cannot find this limitation or setting.   I sent a check with 42