lightsquares and darksquares

These filters are the sets of lightsquares and darksquares respectively.

K on darksquares
matches a position where the white king is on a dark square.
 countsquares 2 10
  B on lightsquares
matches a position where white has at least two bishops on same colored squares (because reflecting a light square about the vertical bisector of the board gives a dark square).

A. Troitzky
.c Tidskrift for Schack#106

flipvertical {not [Aa] on lightsquares
                 countsquares 10 32 [Aa]}
The CQL code above matches a position where all pieces, and at least 10, are on the same color square. The results are sorted by the number of pieces in the position. One of these positions is pictured.