Assertion: checkmate's piece | /r/AtLocation | rare cases
Facets:
Source sentences:
text: the file of departure (if they differ); or the rank of departure (if the files are the same but the ranks differ); or both the file and rank of departure (if neither alone is sufficient to identify the piece—which occurs only in rare cases where one or more pawns have promoted, resulting in a player having three or more identical pieces able to reach the same square).