J3/10-178r1

To: J3
From: Van Snyder/Stan Whitlock
Subject: Interpretation concerning loop termination
Date: 2010 June 14

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NUMBER: F08/0028
TITLE: Does a procedure reference cause loop termination?
KEYWORDS: branch, transfer of control, loop termination, procedure
          reference
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Consider the following DO construct

  DO
    CALL SUB
  END DO

According to subclause 8.1.6.6.4 [177:28-29], loop termination occurs
when

"Control is transferred from a statement within the range of a DO
construct to a statement that is neither the <end-do> nor within the
range of the same DO construct."

A subroutine reference is a transfer of control.

The first executable statement of SUB is not within the range of the DO
construct.

Does the loop terminated when SUB is invoked?

ANSWER:

It is not intended that execution of a DO construct be terminated by a
procedure reference.  Edits are provided to correct this.

EDITS to 10-007:

Replace the fourth item in the bulleted list in subclause 8.1.6.6.4 Loop
termination [177:28-29] with the following:

"o A branch occurs within the range of a DO construct and the branch
   target statement is neither the <end-do> nor within the range of the
   same DO construct."

SUBMITTED BY: Van Snyder

HISTORY: 10-178    m192  F08/0028 submitted
         10-178r1  m192  Draft answer

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