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From Howard Chu <...@symas.com>
Subject Re: Question about new OC addition to the schema
Date Sat, 12 Dec 2009 23:25:57 GMT
Emmanuel Lecharny wrote:
> Another Q :
>
> what should we do if we create an OC containing an AT (in MAY or MUST,
> that's irrelevant) which is already present in one of it's parents ?
> Should it be considered as an error ?
>
No. X.501 is quite clear on this. Section 8.3 "Object Classes"

 >>>
The specification of an object class identifies whether an attribute is 
mandatory or optional; this specification also
applies to its subclasses. The subclass may be said to inherit the mandatory 
and optional attribute specification of its
superclass. The specification of a subclass may indicate that an optional 
attribute of the superclass is mandatory in the
subclass.
<<<

So it's explicitly allowed for a subclass to turn a parent MAY into a MUST. 
(And by omission, it's not allowed to turn a MUST into a MAY.)

Also, object classes support multiple inheritance. I'm pretty sure you'll find 
many legitimate cases of an attribute appearing in multiple instances in an 
inheritance chain.

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

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