VHDL Issue Number:      0229
Classification:         Language Definition Problem
Language Version:       VHDL-87
Summary:                "all" and "others" of limited use in attribute
                        specifications.
Related Issues:
Relevant LRM Sections:
Key Words and Phrases:  User Defined Attributes
Current Status:         Submitted
1076-1993 Disposition:  Closed (All Issues Completely Addressed)
Disposition Rationale:  LRM is clear now, as discussed in 5.1.
Superseded By:          N/A
-----------------------
Date Submitted:         1991/03/21
Author of Submission:   Clive Charlwood
Author's Affiliation:   Synopsys Inc.
Author's Post Address:  1098 Alta Ave.
                        Mountain View, CA 94043
Author's Phone Number:  (415) 962-5425
Author's Fax Number:    
Author's Net Address:   crc@synopsys.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
----------------------
(This was Endot VHDL LRM Trouble Report #JM13           9/20/88)

Consider the following VHDL declarations:

        signal S1, S2, S3 : bit;                        -- #1
        attribute drive : integer;                      -- #2
        attribute load  : integer;                      -- #3
        attribute drive of S1 : signal is 4;            -- #4
        attribute drive of others : signal is 3;        -- #5
        attribute load of all : signal is 3;            -- #6

This is not legal VHDL because after "others" is used with entity class
"signal" in line #5, any further attribute specifications for that entity class
are prohibited.  In effect, you can only use "all" or others for one attribute
of an entity class.  For all other attributes, you must do your attribute
specification explicitly.


Proposed Resolution
-------------------
This is only one of the examples of how badly the definition of this feature
was botched.  The fact that attributes may not be attached to ports, and the
restrictions in the last paragraph of Section 5.1, make the feature almost
useless.  Eliminate the whole User-defined-attribute feature.

Endot is providing UDA's per the LRM.


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


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


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