From Cambridge University Caving Club - CUCC wiki
The MD5 hash of the $1text parameter, or the $1prependtext and $1appendtext parameters concatenated. If set, the edit won't be done unless the hash is correct.
The MD5 hash of the $1text parameter, or the $1prependtext and $1appendtext parameters concatenated. If set, the edit won't be done unless the hash is correct.