Visual Combat Recorder/Recording. A file containing information about battles you fought, respectively the program used to play it.
In VGA Planets, battles work as follows: the Host stores all the starting parameters of the fight in a file, along with a starting value for the random number generator. From this information, the VCR player can reconstruct the whole outcome of the battle. It must use the very same algorithm as the host for that.
This is the reason why PHost battles must be played with PVCR, not the standard VCR. Any other program that replaces parts of the combat comes with an own VCR, too. In DOS Planets, you usually replace the vcr.exe file. In Winplan, there's no such hook, you have to invoke the VCR manually.