A black moves to the vacant mating square of the bK and is captured there by a white piece; the bK then captures this white piece (a special case of the Kniest theme). If the capturing white unit is a pawn, the theme is usually called pawn-Zajic.
White Zajic theme: the roles of white and black thematic pieces are reversed.
Die Schwalbe, 1978
Rice, John Michael
The Problemist, Zajic TT, 2001
feenschach, P. Kniest MT, 1999