The Free On-line Dictionary of Computing (30 December 2018):

Longitudinal Redundancy Check
Block Redundancy Check
LRC

    (LRC, Block Redundancy Check) An
   error checking method that generates a longitudinal parity
   byte from a specified string or block of bytes on a
   longitudinal track.

   The longitudinal parity byte is created by placing individual
   bytes of a string in a two-dimensional array and performing
   a Vertical Redundancy Check vertically and horizontally on
   the array, creating an extra byte.  This is an improvement
   over the VRC because it will catch two errors in the
   individual characters of the string, beyond the odd errors.

   (2004-01-26)