Re: Significance of name forms.

[Howard Chu <hyc@symas.com>]

Michael Ströder wrote:
> Howard Chu wrote:
> > Michael Ströder wrote:
> > > On 2015-04-30 13:37, Howard Chu wrote:
> > > > No. Name forms are only used when a DIT Structure Rule references them.
> > >
> > > Are you sure? If yes, then please point out what's missing herein:
> >
> > PS: you should read X.501(1993) for the exact text, since LDAP must
> > conform to
> > that spec. Section 12.6.
> >
> > http://www.itu.int/rec/T-REC-X.501/en
>
> Hmm...
>
> In X.501(1993) and X.501(2010) it is simply assumed that there are
> *always* DIT structure rules.
>
>  From X.501(1993) section 12.6.5 and X.501(2010) section 13.7.5:
> "Each object and alias entry is governed by a single DIT structure rule"
>
> But there's no text dealing with the LDAP implementation without
> governing structure rule of an entry.

Name Forms are a component of DIT Structure Rules. If you don't use DIT 
Structure Rules, then you don't have name forms either.

> > > http://www.stroeder.com/img/LDAP_Schema_References.png
>
> Also after re-reading X.501 it seems the diagram is correct.
>
> This statement in my former posting is obviously corrent:
>
> "You cannot use DIT Structure Rules without associated Name Forms."
>
> Because connecting the governing with the superior structural rule
> cannot be done without name forms.
>
> > > The governing structure rule might limit the set of possible structural
> > > object classes in a part of a DIT but if absent or not applicable you
> > > can still limit to possible name form(s) for a chosen structural object
> > > class.
> >
> > No, if there are no DIT structure rules then there are no constraints
> > whatsoever on the naming or placement of entries.
>
> I did not find any text in X.501 or RFC 4512 which clearly says that.
> Especially RFC 4512 makes DIT structure rules optional. Maybe I'm
> missing something though.

12.6.2

A name form is only a primitive element of the full specification 
required to constrain the form of the DIT to that
required by the administrative and naming authorities that determine the 
naming policies of a given region of the DIT.
The remaining aspects of the specification of DIT structure are 
discussed in 12.6.5.

12.6.5 defines DIT Structure Rules.
> I also vaguely remember having seen RFCs or I-Ds specifying name forms
> without DIT structure rules. Which of course also is not a sufficient
> proof that name forms apply without DIT structure rules though.
>
> Please don't get me wrong. I just want to clarify this. Because the
> truly optional use of DIT structure rules and name forms is a difficult
> and maybe under-defined topic.

It is completely defined. Name Forms have no meaning on their own. They 
only have any significance when used in a DIT Structure Rule.

--
  -- Howard Chu
  CTO, Symas Corp.           http://www.symas.com
  Director, Highland Sun     http://highlandsun.com/hyc/
  Chief Architect, OpenLDAP  http://www.openldap.org/project/