To: J3                                                     J3/23-151
From: Van Snyder
Subject: A[w] and AT format for objects of enumeration type
Date: 2023-March-25
References: 23-007

Introduction
------------

The only input/output method to transfer data for objects of enumeration
type is integer editing. They are not permitted with list-directed
editing. Clause 12 and subclause 13.11 are silent about whether they are
permitted for namelist editing. Input/output of objects of enumeration
type therefore isn't any different from the situation in Fortran 77. One
still needs to instruct users "Use 1 for red, 2 for green, 3 for blue."
But it does preserve "Fortran's beloved tacked on look" and the
tradition of half-measures that result in programs being littered with
kludges to cope with incomplete features.

Proposal
--------

Allow list-directed and namelist editing for input and output of objects
of enumeration (not enum) type.

Allow A[w] editing for input and output, and AT editing for output, of
objects of enumeration (not enum) type.

Suggested edits
---------------

These suggested edits to 23-007 are provided only to estimate the scope
of the editorial project. Implementation would be complicated by the
possibility to need tables of enumerator names in each scoping unit, or
at least tables that override pieces of tables the processor brings into
the scoping by use association, in case one they are renamed during use
association.

[242:3-4 12.6.3p6 Data transfer input/output list] Replace the
paragraph:

"A list item that is of an enumeration type in a formatted data transfer
statement shall correspond to an A, AT, I, B, O, or Z edit descriptor,
except that such an input item shall not correspond to an AT edit
descriptor."

[281:18-20 13.7.4p1 Character editing] Insert "or enumeration type" after
"type character" twice. Insert "or data of enumeration type" after
"character data".

[281:22+ 13.7.4p1+ Character editing] Insert a paragraph:

"The character length for an output item of enumeration type is the
number of characters in its local name. The character length for an
input item of enumeration type is the greatest number of characters in
the local names of all enumerators of the type."

[281:26 13.7.4p3 Character editing] Replace "the effective item" with "an
effective item of type character."

[281:29+ 13.7.4p3+ Character editing] Insert a paragraph:

"If the effective input item is of enumeration type the length of the
input item shall not be greater than <w>. The value of an output item is
the local name of the enumerator. The case of the output value is
processor dependent. The numeric value of the input item becomes the
numeric value of the enumerator whose local name is the same as the
input value, without regard to case."

[288:35+ 13.10.3.1p9+ List-directed input forms] Insert a paragraph:

"When the next effective item is of enumeration type, the input form
consists of the local name of an enumerator of the type. The numeric
value of the input item becomes the numeric value of the enumerator
whose local name is the same as the input value, without regard to
case."

[290:20+ 13.10.4p7+ List-directed output] Insert a paragraph:

"The character sequence for output of an object of enumeration type is
the local name of the enumerator. The case of the output value is
processor dependent."

[293:14+ 13.11.3.3p8+ Namelist input values] Insert a paragraph:

"When the next effective item is of enumeration type, the input form
consists of the local name of an enumerator of the type. The numeric
value of the input item becomes the numeric value of the enumerator
whose local name is the same as the input value, without regard to
case."

[294:16+ 13.11.4.2p1+ Namelist output editing] Nothing is needed here
because "namelist output records are edited as for list-directed output."

[552:2+ A.2 Processor dependencies] Insert a list item:

" o the case of output of objects of enumeration type (13.7.4);

[552:9+ A.2 Processor dependencies] Insert a list item:

" o the case of output of objects of enumeration type (13.10.4);

Related useful addition
-----------------------

It would be useful to have a CASE changeable mode to specify the case of
variable names in namelist output, and the case of enumeration type
names in namelist and list-directed output. Values might be "UPPER",
"LOWER", or "PROCESSOR_DEPENDENT". There ought to be no controversy here
about what "upper case" and "lower case" might mean, which was the
argument used against intrinsic functions for case conversion because
those terms are difficult to define for ISO 10646 data.