Optional Matching Rule Assertion Syntax

["Steven Legg" <steven.legg@adacel.com.au>]

I've noticed that the 4th edition of X.501 corrects a long standing defect
in the MatchingRuleDescription ASN.1 type. The MatchingRuleDescription
type mirrors the MATCHING-RULE information object class so that matching
rule definitions can be carried in protocol (information objects cannot
be encoded). The 2nd edition definition of the MATCHING-RULE information
object class allowed the assertion syntax (the SYNTAX field) to be omitted,
so that matching rules with a variable assertion syntax could be supported.
Unfortunately, the 2nd edition definition for MatchingRuleDescription had
the assertion syntax (the "information" field) as a mandatory component.
The 4th edition now makes the information field OPTIONAL, the way it
should have been in the first place.

The LDAP string encoding for the Matching Rule Description syntax adheres
to the flawed X.501 MatchingRuleDescription in making the SYNTAX field
a mandatory term. I'd like to see this corrected in the successor to
RFC 2252 to make the SYNTAX field an optional term.

The Adacel implementation has a number of private matching rules where
the assertion syntax is variable. In my component matching rules draft
I need to define additional rules that also have a variable assertion
syntax. At the moment I have no standard defined way to encode their
definitions as a value of the Matching Rule Description syntax.
The alternative is for me to define an LDAP syntax which is taken to
mean "a variable assertion syntax". Making the SYNTAX field optional
is a cleaner, more consistent, solution.

Comments ?

Regards,
Steven