What is this mode of vi?

Have you ever seen this WWW-page?:

http://iki.fi/liw/texts/vi.html

Normally I can get out of vi or Vim via commands ":q" or ":wq". In Vim I
sometimes even use ":wqall". But sometimes I accidentally make Vim to go
to such mode where those key sequences do not work and I need to give
key sequence "Control-Q Control-C ESC Z Z". Latest time was few hours
ago and I had to open up that WWW-page to get out of my Vim.

Can you tell me, what is that mode, where such key sequence is needed?
What key sequence takes me to that mode? What part of Vim-documentation
tell more about that state? Insert, Command, Open etc. are familiar
modes modes for me, but that afore-mentioned mode is something really
weird.


--
Juhapekka "naula" Tolvanen * http colon slash slash iki dot fi slash juhtolv
"Boku wa ongakuka dentaku katate ni. Tashitari. Hiitari. Sousa shite.
Sakkyoku suru. Kono botan oseba ongaku kanaderu." Kraftwerk

On 2008-08-19, Juhapekka Tolvanen wrote:
>
> Normally I can get out of vi or Vim via commands ":q" or ":wq". In Vim I
> sometimes even use ":wqall". But sometimes I accidentally make Vim to go
> to such mode where those key sequences do not work and I need to give
> key sequence "Control-Q Control-C ESC Z Z". Latest time was few hours
> ago and I had to open up that WWW-page to get out of my Vim.

Are you sure that this is actually a vi mode? It seems to me to
be a 'catch-all' sequence designed to get back to a known state
when it isn't known what has happened. ^Q is the Xon character
and will restart terminal output that has previously been stopped
by Xoff (^S). (Try this at a shell prompt by cat'ing a lengthy
text file, e.g. termcap and hitting ^S and ^Q to pause and restart
the output.) If in command mode ^C will have the effect of abandoning
any half-entered command without executing it. The ESC ensures
that you are in fact in command mode ready for the commands that
follow. In short there's nothing magical about it, it is simply
a combination of fixes that address several ways the state may have
been screwed up.

--
Andrew Smallshaw
andrews@sdf.lonestar.org