J3/10-246
To: J3
From: Stan Whitlock
Subject: F03/0096 Can a read statement change the unit value?
Date: 2010 October 13

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NUMBER: F03/0096
TITLE: Can a read statement change the unit value?
KEYWORDS: Read statement, unit value
DEFECT TYPE: Erratum
STATUS: J3 consideration in progress

QUESTION:

Is it allowed to change the value of a variable which supplies the
unit number to an read statement?

10-007 [243:3-5] says the value of any input/output specifier shall not
depend on any input-item.  UNIT= is a specifier in a READ statement.

Note 9.40 on page 221 gives the example

         READ(N)  N, X(N)

and discusses how the changes to N work.

ANSWER:

Yes, the example was intended to be allowed as long as N is not an
internal unit.  Edits will limit the restriction to "output items"
n the specifier list and the Format.

EDITS: In 10-007

[243:3]  In the 5th paragraph of 9.12, replace "The value of a
specifier" with "The value of an <internal-file-variable> or of a
FMT=, ID=, IOMSG=, IOSTAT= or SIZE= specifier"

SUBMITTED BY: Dick Hendrickson

HISTORY: 07-266    m181  F03/0096 submitted
         07-266r1  m181  Draft answer - withdrawn, no reason, no vote
         10-xxx    m193  Draft answer for F2008