What is the maximum number of variables I can use to trigger an archive?

There is no limit to the number of fields defined in the Trigger2Archive option. The INI file is, probably, limited to 16,000 values.

This group normally resides in the FAPARC.INI file. For versions 8.5 or higher the Trigger2Archive control group can reside in any of the INI files. The hierarchy is:

FSIUSER.INI
          FSISYS.INI
                   FAPARC.INI

In the Trigger2Archive control group, be sure to list the APPIDX.DFD file field name on the left side of the equation and the TRNDFDFL.DFD file field name on the right side of the equation. The APPIDX.DFD file field name you specify will be the name you use to save to the archive file.