Epson GT-6500 EN - Manual (Page 143)

ESC B and other commands
This command is not available if a value other than 01
H
(1 bit per
pixel per color) and 02
H
(2 bits per pixel per color) is specified with
the ESC D (Set data format) command.
If a user-defined dither pattern is specified when none has been
downloaded, the Dither mode A is selected.
The parameter 03
H
is effective only when ESC D 01
H
is specified.
Text Enhancement Technology is available only when or
monochrome reading is specified with ESC C.
Command Reference 3-49