Epson GT-6500 EN - Manual (Page 99)

Handshaking
Shows a diagram indicating the handshaking method used with the
command. See Chapter 2 for details on handshaking.
Parameter range
Shows the range and explains the meanings of parameters, when
relevant. This section also lists the default values.
Explanation
This gives a detailed explanation of the effect and appropriate usage
of the command.
Functional level
Lists values such as B1 and B4 on the command line and in the
parameter range to indicate the ESC/I function level of the command.
See Chapter 2 for details.
Command Reference 3-5