Epson 4500 - Manual (Page 115)

Enhancing Your Printing
The print quality and font must be set separately, using SelecType or
the ESC x and ESC k commands. There are two more things to
consider when using the Master Select command:
l
Master Select cancels any of the other listed features that you do
not set. For example, if you have already set a different character
width and you use Master Select to set emphasized double-strike,
the character width is reset to 10 cpi.
l
Proportional spacing overrides 10, 12, and 15 cpi.
4-8 Software and Graphics