Solution or Workaround
Converting a DLG optional file produces the error "DLGARC: standard file format detected".
This error occurs using the STANDARD option as well. The conversion works correctly using ArcInfo 7.0.4.
The DLG file is in DOS format, therefore at the end of each line there is a carriage return character (^M). The DLGARC command in Version 7.1.1 does not accept any non-ASCII characters, also it does not accept any characters beyond the 80th column. Optional DLG data should have 80 characters per line.
Run "dos2unix" command on the DLG file before DLGARC processing. If using Windows NT, download the dos2unix utility for free from the site below.
Click on "Dos Index" and do a local search on dos2unix.