An html version of Prokes.cql which is not in the cql.zip file. Created by Gady Costeff.

; The Prokes manoeuvre is a square-vacating anti-promotion combination
(match
 :pgn heijden.pgn
 :output Prokes.pgn
(position Kd2 pc2 pb2 Ra1 k[a-h4] :moveto .a4 :movefrom Ra1 :attackcount a .a4 1 10
:flipcolor :shifthorizontal :flipvertical)
)

 

After executing this with "> cql Prokes.cql" there are 9 studies found in the Harold van der Heijden Database 2015.
NB. When you see {MATCH} in the text, it means that cql has found the position asked for.

Below only 4 studies presented: