For example [of hints], in the Alto [Lampson, B.W. and Sproull 79] and Pilot [Redell, D.D. et al 80] operating systems, each file has a unique … [that] contains the identifier of the file which … file is called the leader page and contains, … directory. This is the truth on which the … [Directory information for locating files is only hints that must be confirmed before a file is used].
Google-1
Google-2
Copyright clearance needed for quotation.