The player filter takes either a single quoted string, or the name of a color followed by a quoted string, e.g.
    player "Ivanchuk"
    player black "Carlsen"
    player white "Kasparyan"
It matches a game whose player field contains the given string. It can be specified as a CQL parameter or in the body of the CQL file. As illustrated in the sample file gameinfo.cql, it works with flipcolor and can be used to find wins by a player:
  {player white "Ivanchuk"
   result 1-0}
  will find games that Ivanchuk wins (because flipcolor transforms both the player and the result, as they are both enclosed in a braces.