Carl-Uno, you are right that interoperable implementations are not
REQUIRED for publication as an IETF 'Proposed Standard'. Nonetheless,
interoperable implementations are RECOMMENDED (see the excerpt below),
and are common practice in protocols submitted as 'Proposed Standards'
for intermediate systems (routers, hubs, bridges, etc).
Cheers,
- Ira McDonald (outside consultant at Xerox)
906-494-2434
page 8:
4.1.2. Draft Standard Protocol
The IESG is actively considering this protocol as a possible
>> Standard Protocol. Substantial and widespread testing and comment
>> are desired. Comments and test results should be submitted to the
>> IESG. There is a possibility that changes will be made in a Draft
Standard Protocol before it becomes a Standard Protocol.
4.1.3. Proposed Standard Protocol
These are protocol proposals that may be considered by the IESG
>> for standardization in the future. Implementation and testing by
>> several groups is desirable. Revision of the protocol
specification is likely.