An html version of UnguardedGuard.cql; This file in not in the download cql.zip.

Created by Tim Krabbé.

CQL 5.1
; white interposes an unguarded officer to stop a check cql(input heijden.pgn result 1-0) wtm attacks ([rbq] K) piece $guard in [RBNQ] next( move from $guard to . attacks 0 (A $guard) )

CQL 3.2
;;Find positions with white to move such that white ;;is in check from a sliding piece and ;;on white's next move interposes a piece that is unguarded (match :pgn heijden.pgn :output UnguardedGuard.pgn (position :wtm :moveto .d4 :check :or ((position :rayorthogonal ([qr] .d4 K)) (position :raydiagonal ([qb] .d4 K)) ) :sequence ((position) (position :attackcount A Ad4 0) ) :shift :markall) )
After executing this with "> cql UnguardedGuard.cql" there are 1545 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 10 studies are presented: