PS2 3 and 4 are sub-prompts, when for example you enter a multi-line command.
IF you have the Bash docs,
see bash and do a / stringsearch for PS1 for more.
"man" Bash
Also see
"man" console_codes
for console codes, and
"man" binedit
for how to edit e.g. /configuration/profile as binary.
RIGHTS
Copyright 1999 Richard Allen Hohensee
This file is released for redistribution only as part of an intact entire
cLIeNUX Core.