IBM used a dirty trick in the 5703-XM1 source code:

       DC    AL(@CADDR)(#$$KDI)        SECTOR LOAD ADDR
       ORG   *-1    << --- !!          LAST BYTE NOT USED
       DC    CL7'DISPLAY'              KEYWORD

During link-edit on the S/3 a 'P 20 error is issued.
TXT is out of sequence / overlay.

This test can be suppressed with the following patch in
module $OLBE at loc x'11DD' change C0 12 1511 ==> C0 80 1511 (NOP Br)

HJS 2020