J3/17-109
To: J3
From: John Reid & Bill Long
Subject: CHANGE TEAM rewording
Date: 2017 January 13

Discussion
----------

The first sentence of 11.1.5.2 Execution of a CHANGE TEAM construct
says "The values of the <team-variables> on the active images of the
team shall be those of team variables defined by synchronized
executions of the same FORM TEAM statement (11.6.9) on all active
images of the current team." This is incorrect when the
<team-variables> have been defined by executions a FORM TEAM statement
on a team that is a proper superset of the current team. Here is an
example

   TYPE (TEAM_TYPE) OUTER, MIDDLE, INNER
   ...
   OUTER = GET_TEAM()
   FORM TEAM (MIDDLE, MOD(THIS_IMAGE(),2)==1)
   CHANGE TEAM (MIDDLE)
      ...
      FORM TEAM (INNER, MOD(THIS_IMAGE(),2)==1)
      CHANGE TEAM (INNER)
         ...
      END TEAM
   END TEAM

If OUTER has at least 4 images, the teams will be properly nested,
with MIDDLE having about half the images of OUTER and INNER having
about half the images of MIDDLE.

Now suppose the inner construct contains the construct

    CHANGE TEAM (MIDDLE)
      ...
    END TEAM

without any further FORM TEAM statement for MIDDLE. The conditions in
the sentence quoted at the start of this paper are satisfied, but we
do not think it was intended for this to be allowed. This new
construct would execute in teams that are proper supersets of their
parent team.  We need to require that the current team when the FORM
TEAM statement was executed is the current team. The edit proposed
will make the sentence read

"The values of the <team-variables> on the active images of the team
shall be those of team variables defined by synchronized executions of
the same FORM TEAM statement (11.6.9) when the current team was the
team that is now the current team."

Edit to 17-007
--------------

[188:7] In 11.1.5.2 Execution of a CHANGE TEAM construct, para 1,
sentence 1, change "on all active images of the current team." to
"when the current team was the team that is now the current team."