tmpfs -- where's the M to R?

[dman]

I'm interested in tmpfs for several reasons, one of them is setting up
a diskless terminal.  I found a few mentions of tmpfs in the FAQ and a
brief mention in the Multi Disk Tuning HOWTO, but I couldn't find any
docs on it.  Most of what I read said that there was no tmpfs
implementation in Linux, but my config (kernel 2.4.8) says there is.
Any pointers to documentation would be appreciated.

TIA,
-D

(PS.  Please CC any responses to me.)