In chess, a back-rank checkmate (also known as a corridor mate) is a checkmate delivered by a rook or queen along the opponent's back rank (that is, the row closest to them) in which the mated king is unable to move up the board because the king is blocked by friendly pieces (usually pawns) on the second rank.
Beginners are more likely to succumb to back-rank checkmate, as they are more likely to miss threats in general. At higher levels of play, though the mate itself does not occur very often, play is often affected by the possibility of it—being forced to prevent the mate at all costs may leave a player vulnerable to other threats and tactical ideas they might be more likely to miss.
Convert all the letters in the checkmate into numbers A=1, B=2... Y=25, Z=26 etc..
BACKRANKMATE = ABCDEFGHIJKL
The cache can be found at:-
N55 (D-H)(L+B). B(L+C)(D-C)
W001 (G-H)(I-D-A). (K-E-A)(H-A)(E/A)