A non-line piece (pawn or king) clears the line for a line piece in two or more steps.
The idea was suggested by Aleksey Oganesyan in the RU-Chess-Art blog. The term was coined by Viktoras Paliulionis.
See also: Bristol; Step-by-step Bristol.
Oganesyan, Aleksey
Pat a Mat, 2017
2nd-4th Prize
a) 1.f1=R
a4
2.Rf5
a5
3.Rh5
Ra4#
b) 1.f1=B
exf6
2.Be2
fxg7
3.Bh5
Bf6#
Chepizhny, Viktor
Zadachi i etyudy, 2007
6th HM
a) 1.Qf8
a4
2.Ke8
a5
3.Bf7
Qa4#
b) 1.Bd7
Ke1
2.Ke6
Kf1
3.Qf7
Qe1#
FEN: 4q2r/5k2/4b3/2p2p1n/2Pp3B/1P1p1pp1/PP1P4/Q2K4
External links:
Abdurahmanović, Fadil
SuperProblem, 2017
1...c4
2.Rd5
c5
3.Rc4
Sc6#
1...cxd3
2.Sc4
dxe4
3.Bd3
Sf5#