About of PS Format:
PostScript is a page description language, a protocol that is used to communicate between applications (like QuarkXPress, or MS Word) and output devices, like laser printer or imagesetters, that are equipped with a PostScript interpreter.
Setting of PS Format:
Set the language level of the generated PS file. Language level 1.5 is language level 1 with color extensions. Currently language level 3 generates the same PostScript as 2.