by H.G.Muller » 31 May 2015, 10:49
ICS = Internet Chess Server, like FICS or ICC.
A variant is a specific way to play the grand game of Chess, like Bughouse, Suicide or FIDE.
The text is interpreted for historic reasons, because there was a time where the Event tag was the only PGN tag that contained information of what Chess variant it was about. E.g. it would say something like
[Event "FICS suicide game"]
and from that you would have to conclude that the game notation was not for a game of orthodox Chess, but for a game of Suicide Chess.
Currently WinBoard writes a non-standard 'Variant' PGN tag for games that are not orthodox Chess, but as it is non-standard games saved by other interfaces, or by old versions of WinBoard, might not contain it.
I am not sure how precise recognition of a variant name from the Event string is. I would imagine it only recognizes 'wild' variants if the contain the word 'wild', or a one-letter word 'w', followed by a number, and not somthing like "Warsaw 2014".