To: J3                                                     J3/22-158r1
From: Robert Corbett
Subject: BLOCK construct syntax
References: J3/22-007r1
Date: 2022-July-18

Consider the program

        REAL X
        DATA X/0.0/
      END

This program does not use any obsolescent syntax.  The
DATA statement is a declaration construct in the
specification part of the main program.

Next consider the program

        BLOCK
          REAL X
          DATA X/0.0/
        END BLOCK
      END

This program does use obsolescent syntax.  Here, the
DATA statement is an execution part construct in the
block of the BLOCK construct.  A DATA statement that
appears as an execution part construct is obsolescent
syntax.  Item (2) of the list in subclause 4.2
"Conformance" requires a conforming processor to be able
to detect and report use of obsolescent features.  The
obsolescent syntax appears to have been added as part of
the work to make DATA statements among executables
obsolescent.  Note that in this case, the DATA statement
is not among executables.

For now, the only harm is a potential warning message
about a condition which it seems should be allowed.
If the obsolescent syntax is eventually dropped, the
second program will cease being conformant.

There are many ways to allow the second program.  The
edits I propose are the easiest to understand of the
edits I have considered.  When the obsolescent syntax
is dropped, a simpler fix will be possible.

EDITS:

[187:8-9, "11.1.4 BLOCK construct"]
Replace
"[ [ /declaration-construct/ ] ...
   /specification-construct/ ]"
with
"[ /declaration-construct/ ] ..."

[187:14+, "11.1.4 BLOCK construct"]
Insert the constraint
"C1108a The \si{block} of a \si{block-construct} shall
        not begin with a FORMAT statement\obs{or a
        DATA statement}.