Solution or Workaround
This error occurs when trying to load the PATTERNS or TRUETYPE marker sets in the DOS version of ARCPLOT:
ILLEGAL FONT NUMBER -972 [FNTGET]
The error will persists when loading a marker set that worked in previous ARCPLOT sessions.
The PATTERNS and TRUETYPE marker sets are to be used only in the Windows Extension of ARCPLOTW.
To ensure a marker set doesn't interfere when loading another set, use the MARKERSET command with the CLEAR option:
MARKERSET <marker set> CLEAR