Path: utzoo!attcan!uunet!lll-winken!lll-tis!ames!pasteur!ucbvax!ucsd!sdcc6!sdcc12!gr47
From: gr47@sdcc12.ucsd.EDU (gr47)
Newsgroups: comp.os.vms
Subject: Curious as to how Fortran BACKSPACE works
Keywords: Fortran backspace
Message-ID: <1009@sdcc12.ucsd.EDU>
Date: 18 May 88 00:41:10 GMT
Organization: University of California, San Diego
Lines: 19

I am curious as to how Fortran BACKSPACE works.  I vaguely remember
reading in one of the orange manuals that BACKSPACE simply causes
the logical unit to be rewound and read from THE BEGINNING forward to
the record immediately preceding the current one.  Is this true?
How are huge time delays avoided when BACKSPACE'ing large files, or
are delays not avoided?  Or do I remember wrong, and does BACKSPACE
use the saved (?) position of the start of the previous record to do
its task?

My curiosity resulted from looking over AStine's recent attempt at a
TAIL Fortran program.  He tried to useropen a file at the EOF, then
backspace from there, apparently without success.
It would have been nice...

I'd be interested in all commments.

Steve Piper
scpiper@ucsd
scpiper@ucsd.bitnet
cdrgmv::piper2       ! span