Epson AcuLaser C1900 Reference Manual page 352

Font size
The following codes are inserted automatically and need not be
input by hand:
Left/Right quiet zone
Check digit
Start/Stop character
Print sample
EPSON Code39
EPSON Code39 Num
EPSON Code128
Code128 fonts support code sets A, B, and C. When the code
set of a line of characters is changed in the middle of the line,
a conversion code is automatically inserted.
352
Working with Fonts
When OCR-B is not used: 26 pt or more (up
to 96 pt in Windows XP/2000/NT).
Recommended sizes are 26 pt, 52 pt, 78 pt,
and 104 pt.
When OCR-B is used: 36 pt or more (up to 96
pt in Windows XP/2000/NT).
Recommended sizes are 36 pt, 72 pt, 108 pt,
and 144 pt.
EPSON Code39 CD
EPSON Code39 CD Num