The purpose of these scripts program is usually to recover from a crashed console due to an svgalib, Xfree or other program bug.
You do this by being a smart guy and running savetextmode right after booting of your machine, prior to any problems. Then, in case the SVGA state is hosed and you sit in front of a blank or useless console, change VC (maybe login) to get to a shell. Or exist the currently running program with <Ctrl>-C, <Ctrl>-<Alt>-<Backspace>, or whatever applies. Once you got a shell, run textmode and it will hopefully render your console useable again.
To make it clear: You do all this while not seeing anything on your console screen, you enter this information blindly or after logging in from a network. Also, if the keyboard is left in raw mode, nothing can really help you as you cannot enter anything which a shell will understand.
This manual page was edited by Michael Weller <firstname.lastname@example.org>. The exact source of the referenced utility as well as of the original documentation is unknown.
It is very likely that both are at least to some extent are due to Harm Hanemaayer <H.Hanemaayer@inter.nl.net>.
Occasionally this might be wrong. I hereby asked to be excused by the original author and will happily accept any additions or corrections to this first version of the svgalib manual.