To: J3                                                     J3/25-200
From: Van Snyder
Subject: Specifications for US09 -- allow I/O of enumeration type names
Date: 2025-October-26
Reference: 23-151, 23-151r1, 25-007r1

History
=======

23-151 advocated to use "A" formatting for input and output of enumerator
names, "I" formatting for input and output of enumeration-type values
using their ordinal positions, and their names for list-directed input and
output.

23-151r1 advocated to use "G" formatting.

"G" format editing for enumeration-type objects might be considered to
introduce a conflict. Without a specification, perhaps as a changeable
mode, to use enumerator names, one might reasonable belive that "G"
formatting would use the enumerator's ordinal value. 13.7.5 "Generalized
editing" doesn't mention enumeration-type objects, for which editing is
described in 13.7.2.2 Integer editing, which also specifies "The G, B, O,
and Z edit descriptors may also be used to edit integer data." "G" editing
could be used without a problem for input -- if the first character is a
digit, it's the ordinal value; otherwise it's the name -- but it would
remain ambiguous for output.

Specifications are provided for using a combination of both methods.

Specifications
==============

s1. When an object of enumeration type is input or output by Explicit
    format specification methods (13.2):

    s1a. If the corresponding format item specifies character editing
         (13.7.4) its name is used;

    s1b. If the corresponding format item specifies integer editing
         (13.7.2.2) using I, O, Z, or B edit descriptors, its ordinal
         value (7.6.2) is used.

    s1c. If the format item corresponding to the next effective input item
         specifies generalized editing (13.7.5) and the first character of
         the next input value is a digit, integer editing is used;
         otherwise character editing is used.

    s1d. If the format item corresponding to the next effective output
         item specifies generalized editing, whether character or integer
         editing is used is specified by the ENUMERATION (spelling TBD)
         changeable mode.

s2. A changeable mode (12.5.2) shall determine whether generalized output
    editing uses enumerators' names or ordinal values. Spellings of the
    mode name and values are TBD. If the mode is NAME, generalized output
    editing shall use the enumerator's name. If the mode is ORDINAL,
    generalized output editing shall use the enumerator's ordinal value.
    If the mode is DEFAULT, whether generalized output editing uses
    character or integer editing is processor dependent.

    {Changeable modes can be specified by an OPEN statement or format
    item, and inquired by an INQUIRE statement. The format item might be
    EN (without w.d or w.dEe) for NAME, EO for ORDINAL, or ED for
    default.}

s3. List-directed (13.10) and namelist (13.11) editing shall use
    generalized editing for objects of enumeration type. If the first
    character of an input value is not a digit, or the first character
    after the asterisk in the r*c form, if any, is not a digit, the item
    is edited according to the rules for character editing. See s2 for
    output.

s4. C8109, which already pointlessly prohibits a <namelist-group-object>
    from being of enumeration type, or having a component of enumeration
    type, shall be removed.

    {13.10 List-directed formatting is silent about objects of enumeration
    type.}

s5. During character editing of enumeration-type input items, if the next
    input value is not the name of an enumerator of the type of the next
    effective list item or the corresponding namelist group object, an
    error condition exists.

s6. A changeable mode shall determine whether generalized output editing
    of enumerator names, the "E" or "D" in real values, variable names in
    namelist output, and component names in namelist output, use upper
    case, lower case, or a processor-dependent default.

s7. A changeable mode shall determine whether namelist output of
    structures produces component names.