Epson 5000/5500 - Manual (Page 127)

Using the Command Summary
This printer uses the Epson ESC/P 2 printer control language. You
can use these commands to produce high quality, laser-like
printouts. ESC/P 2 commands provide scalable fonts (Epson Roman
and Epson Sans Serif) and enhanced graphics.
The following section lists and describes all the commands by topic.
If a command has no parameters, it is merely listed. If it has
parameters, they are explained. The parameters are indicated by
lowercase italicized letters, usually n. The examples below show
how the parameters are indicated.
ESC @ is a command with no parameters.
ESC U 1/0 is a command that uses 1 to turn the feature on and 0
to turn it off.
ESC $ n1 n2 is a command with two parameters.
ESC D nn is a command with a variable number of parameters.
8-2 Command Summary