HelpPC 2.10	Quick Reference Utility	Copyright 1991 David Jurgens
TC: int lock( int handle, long offset, long length )        - prototype in io.h        - locks arbitrary, non-overlapping regions of any file (DOS 3.X),          preventing reads/writes to those regions        - returns 0 on success, else -1 on error        - all locks must be released before program termination        - MS C uses locking()        - see   unlock()
Esc or Alt-X to exit	lock (C)	Home/PgUp/PgDn/End ←↑↓→