Rockwell Automation 8520-ARM2 9/Series CNC AMP Reference Manual Documentation Set - Manual (Page 397)

Axis Program Format Parameters
Chapter 16
16-5
Function
This parameter specifies whether a part program format error is generated
if a letter is programmed without a succeeding numeric digit (for example,
programming the block XYZ; would generate an error). When this
parameter is disabled, the control assumes a value of zero for any letter
programmed without a numeric digit.
Axis Parameter
Number
All [406]
Range
Selection Result
(a) Enabled
(b) Disabled
Notes
This is a global parameter; the value set here applies to all axes and processes.
END OF CHAPTER
16.5
Error if Letter Numeric
Missing