A line-piece leaves square X and crosses square Y. Another line-piece moves in the same direction to square Y crossing the square X. According to the purity of aim principle the clearing piece should not have any influence on the subsequent play, the sole purpose of its move should be only to clear the line for the follower.
Alias: Bristol clearance; Bahnung (Ger.).
Sola, Pentti Olavi
Deutsche Märchenschachzeitung, 1932
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Shinkman, William A.
Detroit Free Press, 1884 (corr. 1921)
Israel Ring Tourney, 1967
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Jonsson, Bernt Christer
U.S. Problem Bulletin, 1992
The Problemist, 2014
9th WCCT, 2012
Jones, Christopher James Austin