To: J3                                                     J3/18-166
From: Robert Corbett
Subject: clarifying constraint C926
Date: 2018-June-08
Reference: 18-007

1. Discussion

Constraint C926 in Subclause 9.5.3.1 is a restriction on array
sections with /substring-range/s.  The constraint states

    If a /substring-range/ appears, the rightmost /part-name/
    shall be of type character.

Consider the array section "CHRARY(:N)(I:I)", where CHRARY is
an array of type character and I and N are integer variables.
In this example, the rightmost /part-name/ in the
/substring-range/ is "I".  A sophisticated reader will
understand that the "rightmost /part-name/" referenced here is
"CHRARY".  A naive reader might think that the constraint is
misstated.

The subclause on subtrings, Subclause 9.4.1, contains a parallel
constraint that avoids this possible source of confusion.
Constraint C908 states

    /parent-string/ shall be of type character.

where /parent-string/ is parallels the /data-ref/ in syntax
rule R918. Using similar wording for array sections removes
a possible source of confusion.  The edited version of
constraint C926 would read

    If a /substring-range/ appears, /data-ref/ shall be of
    type character.

An edit is provided.


2. Edit to 18-007

[9.5.3.1 the Syntax portion "Array elements and array sections"
 133:22]  Replace "appears, the ... of type character" with
 "appears, \it{data-ref} shall be of type character".