To: J3                                                     J3/21-185
From: Malcolm Cohen
Subject: Definition of segment
Date: 2021-October-16


1. Introduction

The term "segment" was invented by us, and is a technical term that is not
entirely self-explanatory. Therefore, it should be defined in clause three.

Also, we could have that definition say what a segment is in denotational
terms, rather than being a list of examples. The descriptive form in clause
11 is good to keep as well though.

Finally, the description in clause 11 does not take into account when a
program computes something using the collectives (which are not image
control statements), and terminates with ERROR STOP. If it closed an output
file before error termination, it could even have produced good results!
The current description seems to mean that such a program would have no
segment, which is obviously not what we meant.


2. Edits to 21-007r1

[17:34+] After 3.123.1 block scoping unit, insert new definition

   "3.123a
    segment
    maximal sequence of executions on an image of statements other than
    image control statements (11.7.2)"
{The ref is to the subclause entitled "Segments".
 EDITOR: Hyperlink "image control statements".}

[211:5] 11.7.2 Segments, p1, append
  "If an image does not execute any image control statement, its entire
   statement execution sequence is a single segment."
{Clarify description.
 EDITOR: Hyperlink "segment" throughout this paragraph to the definition.
         Consider hyperlinking throughout this whole subclause (the only
         drawback is that that would make lots of blue text).
         Maybe there are other parts of the standard where hyperlinking
         "segment" would be a good move too.}

===END===