EXFO FTB-500 (Window XP) - Manual (Page 410)

IEEE 488.2 and Specific Command Reference
402 FTB-500
Specific Commands
When the data is returned in ASCII, the
is the number of significant digits to
be returned. A value of zero indicates
that the device selects the number of significant
digits to be returned.
When the data is returned in PACKED ,
the is not used and always returns 0.
Example(s) FORM? returns ASCII,6
FORM? returns PACKED,0
See Also FORMat[:DATA]?
:FORMat[:DATA]?