From The Free On-line Dictionary of Computing (19 January 2023):
Vertical Redundancy Check
VRC
<storage, communications> (VRC) An error checking method
performed on one 8-bit ASCII character, where the 8th bit is
used as the parity bit.
The resulting parity bit is constructed by XORing the
word. The result is a "1" if there is an odd number of 1s,
and a "0" if there is an even number of 1s in the word. This
method is unreliable because if an odd number of bits are
distorted, the check will not detect the error. The
Longitudinal Redundancy Check is an improvement.
(2001-04-28)