To: J3                                                     J3/22-153
From: John Reid
Subject: Established coarrays
Date: 2022-June-11
References: 22-007r1

Discussion
----------

We have not been consistent in our use of the term "established" for a
coarray in a team. It is my belief that rather than there always being
a single team in which a coarray is established we intended to allow a
coarray to be established in the current team and a sequence of
ancestors in which each is the parent of its predecessor. A coarray
being established in a team then means that a set of coindices and a
scalar of type TEAM_TYPE identify an image in the team. This
interpretation is supported, for example, by these words in the
description of the TEAM argument of the intrinsic THIS_IMAGE [447:25-26]
"If COARRAY appears, it shall be established in that team."

The opposite view is given in 5.4.8 which begins with this sentence
[43:2] "A nonallocatable coarray with the SAVE attribute is established
in the initial team." and says nothing about being established in any
other team. I think words to this effect should be added to 5.4.8
"A coarray that is established in the team in which a CHANGE TEAM
statement is executed is established in the team of the CHANGE TEAM
construct".

Edits are proposed to support this view, to correct an error found
during the preparation of this paper, and to make an editorial
improvement.

Edits to 22-007r1
-----------------

[43:11] In 5.4.8 Established coarrays, para 5, sentence 2, add
"nonallocatable" before "coarray" so that the sentence becomes
"A nonallocatable coarray dummy argument is not established in any
ancestor team even if the corresponding actual argument is established
in one or more of them."
{This is a simple error. The current text contradicts the statement in
para 2 of 5.4.8: "An allocated allocatable coarray is established in
the team in which it was allocated."

[43:12+] In 5.4.8 Established coarrays, add new para 6:
"A coarray that is established in the team in which a CHANGE TEAM
statement is executed is established in the team of the CHANGE TEAM
construct".

[140:20] In 9.6 Image selectors, para 3, sentence 1, at the end of the
sentence delete
"or an ancestor thereof" so that the sentence reads
"If a TEAM= specifier appears in an <image-selector>, the team of the
image selector is specified by <team-value>, which shall identify the
current or an ancestor team; the object shall be an established coarray
in that team."

[140:23] In 9.6 Image selectors, para 3, sentence 2, change
"an ancestor" to "the parent" so that the sentence reads
"If a TEAM_NUMBER= specifier appears in an image-selector> and the
current team is not the initial team, the value of the <scalar-int-expr>
shall be equal to the value of a team number for a sibling team of the
current team and the team of the image selector is that team; the
object shall be an established  coarray in the parent of the current
team, or an associating entity of the CHANGE TEAM construct."
[It's the parent that matters. We do not need to mention ancestors of
the parent. ]

[402:15] In 16.9.107 IMAGE_INDEX (COARRAY, SUB) ..., para 3, COARRAY,
sentence 2, change
"an ancestor" to "the parent" so that the sentence reads
"If TEAM_NUMBER appears and the current team is not the initial
team, it shall be established in the parent of the current team."
[It's the parent that matters. We do not need to mention ancestors of
the parent. ]

[402:15] In 16.9.107 IMAGE_INDEX (COARRAY, SUB) ..., para 3, COARRAY,
penultimate sentence replace "Otherwise, if" by "If" so that the sentence
becomes "If TEAM appears, it shall be established in that team."
[Editorial improvement. Makes the meaning clearer.]

[402:16] In 16.9.107 IMAGE_INDEX (COARRAY, SUB) ..., para 3, COARRAY,
final sentence replace "Otherwise" by "If neither TEAM nor TEAM_NUMBER
appears" so that the sentence becomes "If neither TEAM nor TEAM_NUMBER
appears, it shall be established in the current team or an ancestor of
the current team."
[Editorial improvement. Makes the meaning clearer.]