VMS Help DTM, COMPARE, Command Qualifiers, /WIDTH  *Conan The Librarian (sorry for the slow response - running on an old VAX)

   /WIDTH=n

   For noninteractive and interactive terminal tests that were
   compared with the /CHARACTERS or /RECORDS qualifier, the /WIDTH
   qualifier specifies the maximum width allowed for the differences
   report. The minimum width is 48 columns and the maximum width is
   511 columns. The default value is 132 columns.