VHDL Issue Number:      0219
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                Applicability of resolution functions is still unclear.
Related Issues:         0004
Relevant LRM Sections:  2.4
Key Words and Phrases:  Resolution functions, subtype indications,
                        composite signals
Current Status:         Submitted
1076-1993 Disposition:  Superseded (ISAC Issues Outstanding)
Disposition Rationale:  N/A
Superseded By:          1076
-----------------------
Date Submitted:         1991/03/21
Author of Submission:   Paul Menchini for Daniel Barclay
Author's Affiliation:   CAD Language Systems, Inc.
Author's Post Address:  P.O. Box 13036
                        Research Triangle Park, NC  27709-3036
Author's Phone Number:  (919) 361-1913
Author's Fax Number:    
Author's Net Address:   mench@clsi.com
-----------------------
Date Analyzed:          TBD
Author of Analysis:     TBD
Revision Number:        $Revision: 1.9 $
Date Last Revised:      $Date: 1995/08/04 01:45:13 $


Description of Problem
----------------------
The second sentence of the first paragraph of Section 2.4 (on page 2-7) reads:

        Resolution functions are associated with signals that require
        resolution by including the name of the resolution function in
        the declaration of the signal or in the declaration of the
        subtype of the signal.

The wording "the declaration of the subtype" is problematic, specifically
"declaration."  A type declaration may also implicitly declare a subtype.  Is
that subtype "declared" for the purposes of the quoted sentence?  Consider

        type UCAT is array (Integer range <>) of res_whole Bit_Vector(1 to 10);

The clear intent of the language is that signals of some subtype of UCAT be
resolved on an element-by-element basis.  But does the quoted sentence really
provide for this?  It seems that the subtype indication "res_whole Bit_Vector
(1 to 10)" exist as a declared subtype if the quoted sentence is to be
operative.

Note that this same problem also exists for record types whose elements are
individually resolved.


Proposed Resolution
-------------------
Clarify the wording of the quoted sentence to clearly allow the above example.
Additionally, the start of the quoted sentence can be made singular to match
the end of the sentence.  Finally, the phrase "that require resolution" may not
be necessary.


VASG-ISAC Analysis & Rationale
------------------------------
TBD


VASG-ISAC Recommendation for IEEE Std 1076-1987
-----------------------------------------------
TBD


VASG-ISAC Recommendation for Future Revisions
---------------------------------------------
TBD