fp-interop: Update with comments from HPC subgroup

Co-authored-by: Dan Bonachea <dobonachea@lbl.gov>

Author: kc9jud

proposals/fp_interop/25-189r1.txt

@@ -12,6 +12,8 @@ References:
             to ISO_C_BINDING
       ISO/IEC 60559:2020 Floating-Point arithmetic
       IEEE 754-2019 IEEE Standard for Floating-Point Arithmetic
+      25-189 Requirements and specifications for interoperability with C
+            interchange and extended types
 
 
 1 Background
@@ -28,48 +30,47 @@ bg03. This paper contains formal requirements and specifications for
       Fortran 202Y proposal US05, "Add extended floating-point types
       defined in ISO C23 to ISO_C_BINDING".
 
+bg05. The C23 standard adds a large number of new types, importing
+      significant portions of ISO/IEC 60559 (a.k.a IEEE 754) into its
+      specification. During discussion of 25-189 at meeting #237, a
+      straw poll of J3 indicated strong consensus for adding support for
+      extended binary floating types (rq07-rq09) and decimal floating
+      types (rq11), but strong consensus against extended decimal
+      floating types (25-189 rq13) and arbitrary-size floating types
+      (25-189 rq15-rq17). This revision amends the paper to reflect this
+      consensus.
+
 2 Requirements
 ==============
 
-rq01. The C23 standard adds a large number of new types, importing
-      significant portions of ISO/IEC 60559 (a.k.a IEEE 754) into its
-      specification. The most important of these for Fortran
-      interoperability with C are the '_Float16', '_Float32',
-      '_Float64', and '_Float128' types (and their related complex
-      types). Requirements rq02-r05 deal with these new types. Many of
-      the other types, covered by rq07-rq17, are marked as optional and
-      could be dropped independently while keeping the rest of this
-      paper. These optional requirements primarily serve to maintain
-      parity with Annex H of C23.
-
-rq02. The ISO_C_BINDING module should provide integer named constants
+rq02. The ISO_C_BINDING module shall provide integer named constants
       for KIND parameters corresponding to the C interchange floating
       types '_Float16', '_Float32', '_Float64', and '_Float128'.
 
 rq03. If the companion processor defines '__STDC_IEC_60559_BFP__' and
       '__STDC_IEC_60559_TYPES__', then the KIND parameters corresponding
-      to '_Float32' and '_Float64' should equal those corresponding to
+      to '_Float32' and '_Float64' shall equal those corresponding to
       'float' and 'double', respectively.
 
-rq05. The ISO_C_BINDING module should provide integer named constants
+rq05. The ISO_C_BINDING module shall provide integer named constants
       for KIND parameters corresponding to the C interchange complex
       types '_Float16_Complex', '_Float32_Complex', '_Float64_Complex',
-      and '_Float128_Complex'. The values of the named constants should
+      and '_Float128_Complex'. The values of the named constants shall
       equal those of the respective constants for the interchange
       floating types.
 
-rq07. The ISO_C_BINDING module should provide integer named constants
+rq07. The ISO_C_BINDING module shall provide integer named constants
       for KIND parameters corresponding to the C extended floating types
       '_Float32x', '_Float64x', and '_Float128x'.
 
-rq09. The ISO_C_BINDING module should provide integer named constants
+rq09. The ISO_C_BINDING module shall provide integer named constants
       for KIND parameters corresponding to the C extended complex types
       '_Float32x_Complex', '_Float64x_Complex', and
-      '_Float128x_Complex'. The values of the named constants should
+      '_Float128x_Complex'. The values of the named constants shall
       match those of the respective constants for the extended floating
       types.
 
-rq11. The ISO_C_BINDING module should provide integer named constants
+rq11. The ISO_C_BINDING module shall provide integer named constants
       for KIND parameters corresponding to the C interchange decimal
       floating types '_Decimal32', '_Decimal64', and '_Decimal128'.
 
@@ -102,7 +103,7 @@ sp02. To the ISO_C_BINDING module, add the following integer named
 
       If the companion processor defines '__STDC_IEC_60559_BFP__' and
       '__STDC_IEC_60559_TYPES__', then the constants 'C_FLOAT32' and
-      'C_FLOAT64' should have the same values as 'C_FLOAT' and
+      'C_FLOAT64' shall have the same values as 'C_FLOAT' and
       'C_DOUBLE', respectively (C2023 H.2.4.2).
 
 sp05. To the ISO_C_BINDING module, add the following integer named