Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!swrinde!elroy.jpl.nasa.gov!usc!wuarchive!ukma!psuvax1!hsdndev!cmcl2!lanl!jlg
From: jlg@lanl.gov (Jim Giles)
Newsgroups: comp.lang.fortran
Subject: Re: SAVEing FORTRAN variables
Message-ID: <14845@lanl.gov>
Date: 15 Feb 91 19:40:40 GMT
References: <1991Feb15.172635.17261@craycos.com>
Organization: Los Alamos Natl Lab, Los Alamos, N.M.
Lines: 40

From article <1991Feb15.172635.17261@craycos.com>, by pmk@craycos.com (Peter Klausler):
> [...]
> Variables that are initially defined with a DATA statement are static, and
> don't need a SAVE statement.

No.  ANSI X3.9-1978, page B-5, lines 7-11:

      Initially defined entities in a subprogram may become
      undefined at the execution of a RETURN or END statement if
      they are assigned any value, including their initial value,
      during the execution of the the executable program (see 8.9 and
      15.8.4).

And on page 15-15, lines 1-11:

      15.8.4 Definition Status.  Execution of a RETURN statement
      (or END statement) within a subprogram causes all entities
      within the subprogram to become undefined, except for the
      following:

	 [...]

	 (3) Initially defined entities that have neither been
	     redefined or become undefined.

	 [...]

The purpose appears to be to allow (at least) the following
interpretations of initialized (but unSAVEd - PAGAN? :-) variables:

   1) On each entry, the value is again initialized according to the
   DATA statement;

   2) On each entry (except the first), the value is retained from the
   previous instantiation (as if it had been SAVEd);

   3) on each entry (except the first), the value is completely
   unpredictable (just like any other unSAVEd variable).

J. Giles