VHDL Issue Number:      0155
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                Attribute specifications using OTHERS cannot apply to
                        zero entities.
Related Issues:         None.
Relevant LRM Sections:  5.1
Key Words and Phrases:  Attribute specification, others
Current Status:         Submitted
1076-1993 Disposition:  Superseded (ISAC Issues Outstanding)
Disposition Rationale:  N/A
Superseded By:          1023
-----------------------
Date Submitted:         1991/03/13
Author of Submission:   Paul Menchini
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: 1995/05/13 19:34:42 $


Description of Problem
----------------------
The first sentence of Section 5.1 states "An attribute specification associates
a user-defined attribute with *one or more* entities ...."  [Emphasis mine.]
This statement implies that the following VHDL is illegal:

     B: block
          signal S: Bit;
          attribute Foo: Boolean;
          attribute Foo of      S: signal is True;
          attribute Foo of others: signal is False;
        begin
            :
        end block B;

The other uses of "others" in VHDL allow the applicable construct to apply to
zero or more items; e.g., in configuration and disconnection specifications and
in aggregates, case statements, and selected signal assignment statements.

The language in paragraph 2 of Section 5.1 appears to exactly parallel the
language in paragraph 2 of Section 5.2 and paragraph 2 of Section 5.3, which
indicates that the usage "one or more" was probably not intended in Section
5.1.


Proposed Resolution
-------------------
Allow attribute specifications to apply to zero or more entities, specifically
when the entity name list is ALL or OTHERS.


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


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


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