Datamax Prodigy Operator's Manual page 130

Code Subset B includes all of the standard upper case alphanumeric
keyboard characters plus lower case alphabetic and special characters.
To select Code Subset B, precede the data to be encoded with an ASCII
B (DEC 66, HEX 42). If no start character is sent for the 128 font, Code
Subset B will be selected by default.
Code Subset C includes the set of 100 digit pairs from 00 through 99
inclusive, as well as special characters. Code Subset C is used for
double density encoding of numeric data. To select Code Subset C,
precede the data to be encoded with an ASCII C (DEC 67, HEX 43).
You must not try to encode alpha data if you select Code Subset C.
Special Character Handling
Characters above ASCII value 95 are considered special characters. To
access these values, a two character reference table has been built into
the Printer. The following table describes this reference.
ASCII 2 CHAR
95 &A
96 &B
97 &C
98 &D
99 &E
100 &F
101 &G
As an example, to get FNC2 to be encoded into a Code Subset A bar
code, send the ASCII & (ASCII 38, HEX 26) followed by an ASCII B
(DEC 66, HEX 41), code FNC2 will be encoded.
Example:
Data Encoded:
Page - D14
CODEA CODEB CODEC
FNC3 FNC3 –NA–
FNC2 FNC2 –NA–
SHIFT SHIFT –NA–
CODEC CODEC –NA–
CODEB FNC4 CODEB
FNC4 CODEA CODEA
FNC1 FNC1 FNC1
ATEST&B123
TEST<FNC2>123
Appendix D