Pmove_fixed is a game setting (q3 engine) and it can be set on client and also on server side.
/seta pmove_fixed 0
Values: “0” or “1”
The client (you) will be set to the default value of the server where you are playing at.
Basically if you set this in enemy territory to “0” you can jump higher. It can be very useful when you jump on boxes or use trick jumps. There are some boxes or edges you cannot jump on even at more tries, so set this to “1” and you will be able to make those jumps (there are also other settings which can influence this. like: “seta com_maxfps 125”).
One of the functions which is responsible for game physics is Pmove(). This function is run once at every frame of the client side (your side). By running this pmove_fixed function at a fixed rate, it is an attempt to level the playing field (at every pmove_msec milliseconds.) The default pmove_msec (8) is equivalent to normal physics at 1000 / 8 = 125 frames/second. More info here (Thanks to WeblionX)
I heard that there might be a bug in NoQuarter mod if it is set to “1”