sentinel

Computer Science An Overview _J. Glenn Brookshear _11th Edition

Inherent in processing a sequential file is the need to detect when the end of
the file is reached. Generically, we refer to the end of a sequential file as the
end-of-file (EOF). There are a variety of ways of identifying the EOF. One is to
place a special record, called a sentinel, at the end of the file. Another is to use
the information in the operating system’s directory system to identify a file’s
EOF. That is, since the operating system knows which sectors contain the file, it
also knows where the file terminates.