On 25/06/2013 08:38, John C Klensin wrote: > > --On Monday, June 24, 2013 16:28 -0400 Alia Atlas > <akatlas@xxxxxxxxx> wrote: > >> I read SHOULD and RECOMMENDED as different. >> >> SHOULD is how a implementation ought to behave unless there >> are special circumstances (deployment, additional >> functionality, better idea). MUST says that there are no >> circumstances special enough to change the behavior. >> >> RECOMMENDED is closer to a Best Current Practice (BCP); so I >> might write "It is RECOMMENDED that the network-converged >> timer have a minimum value of 2 seconds." but in 10 years, >> maybe it'll only take 2 microseconds - so that'll become a bad >> recommendation! > > And that, again, is close to the distinction that a reasonable > person might read into 2026. But not into 2119 which appears > (at least to me) to make them fully-substitutable alternatives. > > The distinction doesn't make the comments made by Peter, Dave, > or others any less valid. If we told ourselves that readers > should (lower case) infer conformance statements from SHOULD and > applicability ones from RECOMMENDED... well, we would be pretty > delusional. Also, issuing 2119bis with a subtle difference between the two would create a horrible problem of interpretation for all existing documents (including numerous documents from other SDOs) that explicitly cite 2119. This has ramifications that make my head hurt. Brian