Epson GT-6500 EN - Manual (Page 21)

Control Code Construction
Function level
The EPSON image scanner control language currently has the
following function levels: B1 to B5 and A5. The relationship of each
level is shown in the following diagram. Each level contains the
commands and features of all lower levels.
For example, if you are using a B4-level scanner, all programs made
for B1 through B3 levels should run with no problem. All scanners
feature the control codes from lower level machines.
However, some scanner settings are unique to particular scanner
models, so you must take these into account when writing scanner
programs.
Parameters
Some commands require additional parameters. Commands that
require parameters do not take effect until the parameters are sent, so
always make sure you send the correct parameters. Sending an
incorrect parameter may cause a scanner error.
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