Parity
From The Glossary of Digital Photography
An error-checking routine used in computers. An extra bit is added to data so that the data is always even or odd. Parity checking is used when transmitting or storing data.

ONLINE GLOSSARY OF DIGITAL PHOTOGRAPY
An error-checking routine used in computers. An extra bit is added to data so that the data is always even or odd. Parity checking is used when transmitting or storing data.