To: J3                                                     J3/19-180
From:    Jon Steidel and John Reid
Subject: Problems with TEAM_NUMBER= in image selectors
Date: 2019-July-16


1. Introduction
Section 9.6, paragraph 3 explains the semantics of image selectors
that specify TEAM=, TEAM_NUMBER=, or that specify neither.  There are
several problems with this paragraph.

If TEAM_NUMBER= is specified in an image selector, the coarray must
be established in an ancestor team.  This does not allow TEAM_NUMBER=
to specify the team number of the current team and reference a coarray
established in the current team.

The TEAM_NUMBER= specifier in an image selector may specify a value
of -1 if and only if the current team is the initial team. This is
different than the behavior of the TEAM_NUMBER arguments of the
IMAGE_INDEX and NUM_IMAGES intrinsics which allow -1 to indicate the
initial team, no matter what the current team is.

Finally, if neither TEAM= nor TEAM_NUMBER= is specified, nothing is
said as to whether the coarray object has to be established.


2. Interpretation Request

----------------------------------------------------------------------

NUMBER: F18/xxx
TITLE: Problems with TEAM_NUMBER= in image selectors
KEYWORDS: TEAM_NUMBER, image selectors
DEFECT TYPE: Erratum
STATUS: Submitted

QUESTIONS:

Section 9.6 Image selectors, p3 states
"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 team or an ancestor team; the object shall be an established
coarray in that team or an ancestor thereof. 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 one of the teams that were formed by
execution of the FORM TEAM statement for the current team and the team
of the image selector is that team; the object shall be an established
coarry in an ancestor of the current team, or an associating entity of
the CHANGE TEAM construct. If a TEAM_NUMBER= specifier appears in an
<image-selector> and the current team is the initial team, the value
of <scalar_integer-expr> shall be the team number for the initial team;
the object shall be an established coarray in the initial team.
Otherwise, the team of the image selector is the current team."

Question 1:

The TEAM_NUMBER argument to IMAGE_INDEX and NUM_IMAGES is allowed to
have the value -1 to indicate the initial team regardless of which
team is the current team.  The description of the TEAM_NUMBER=
specifier for image selectors allows a TEAM_NUMBER of -1 only when the
initial team is the current team.  Was this difference intended?

Question 2:
If TEAM= is specified and <team-value> is that of the current team, or
if neither TEAM= or TEAM_NUMBER is specified, the team of the image
selector is the current team and the coarray object may be established
in the current team.  If TEAM_NUMBER= is specified and <scalar-int-
expr> is the same as that of the current team, the coarray object
cannot be a coarray established in the current team.  Was this
this exclusion intended?

Question 3:

If neither TEAM= or TEAM_NUMBER= is specified in an image selector,
can the coarray object be a coarray that is not established?

ANSWERS:

Question 1:

No, this difference was not intended.  Edits are provided to correct
this.

Question 2:

This difference was not intended. When the team of an image selector
is the current team, typically neither TEAM= or TEAM_NUMBER= are
specified.  Edits are provided to allow this case.

Question 3:

An unestablished coarray cannot be coindexed. The edits below correct
this oversight.

EDITS to 18-007r1:
9.6 Image selectors p3

Because there will be two ways for the team of the image selector to be
the current team, we think it will be clearer to split para 3 into two
parts, the first explaining how the team of the image selector is
selected and the second explaining how the coarray is required to be
established in the various cases.

[131:16-23]
  at the end of sentence 1, delete "; "the object shall be ... thereof"
  at the end of sentence 2, delete "; "the object shall be ...
  construct"
  at the end of sentence 3, delete "; "the object shall be ... team"

[131:17-18]
  in sentence 2, change "the current team ...  <scalar-int-expr>"
  to "the value of <scalar-int-expr> is positive, it"

[131:22]
  in sentence 3, change "the current team is ... the team number for
  the initial team"
  to "the value of scalar-int-expr is -1, the team of the image
  selector is the initial team"

 making the whole paragraph read
  "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. If a TEAM_NUMBER=
   specifier appears in an <image-selector> and the value of <scalar-
   int-expr> is positive, it shall be equal to the value of a team
   number for one of the teams that were formed by execution of the
   FORM TEAM statement for the current team and the team of the image
   selector is that team. If a TEAM_NUMBER= specifier appears in an
   image selector and the value of <scalar-int-expr> is -1, the team
   of the image selector is the initial team. Otherwise, the team of
   the image selector is the current team."

[131:24+] insert new paragraph
  "If the team of the image selector is the initial team, the current
   team, or an ancestor of the current team, the object shall be
   established in that team or an ancestor thereof.  Otherwise, the
   object shall be established in an ancestor of the current team, or
   be an associating entity of the CHANGE TEAM construct."

SUBMITTED BY: Jon Steidel and John Reid

HISTORY: 19-xxx   m219  Submitted

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