a code which is unique for the file to which it belongs

a "matching number" for checking files

a method of taking a file and boiling it down to a reasonably short number that uniquely identifies the content of the file

an algorithmic file quality and accuracy check

a number which is unique to that file

a number with the property that it changes in case anything in the file changes, i

a way of fingerprinting files

a digital dictation recorders , speech recognition software, out of offline voice files