Re: LDAP Extension Style Guide, re interaction between controls

["Kurt D. Zeilenga" <Kurt@OpenLDAP.org>]

At 05:35 PM 8/23/00 +0100, David Chadwick wrote:
>But what about the case of two controls, both non-critical, both 
>understood in isolation, but the combination not. What does the 
>server do now - selectively ignore one of them? If so which one?

I suggest ignore both under the general principle of least
astonishment.  I suggest:

An operation may be extended by one or more controls.  If the
combination of controls is unrecognized, undefined, or the
server is otherwise unwilling to perform the operation as
extended by the sequence of provided controls,
  if any of the controls are marked critical, the server
  SHALL return unavailableCriticalExtension,
  otherwise the server SHALL perform the operation as if
  no controls were provided.

That is, combined control semantics is all or nothing.