Re: Info on the meaning of LDAP search filters

Eric Rosenquist (
Thu, 11 Jul 1996 14:04:22 -0400

On 11 Jul 96 at 10:07, Alex Hwang wrote:

> RFC1558 defines the syntax. But I cannot find the formal semantic
> definition of these filter strings. For example, what does <approx>::
> '~=' mean? Does it work for both numbers and string?

You'll have to look through the X.500 specs for that info - the meaning of
an approximate search is dependent on the attribute syntax, and even then,
some of it is DSA-implementation specific. X.511(92) had no specific
guidelines, stating only that "if approximate matching is not supported,
[it] should be treated as a match for equality". The last 1993 draft I
saw didn't change this area much, so the general answer is that it is DSA
and attribute syntax specific.

Most DSAs implement a soundex algorithm on string types, and probably
nothing for numeric types.

Eric Rosenquist, Strata Software Limited
Email: Tel: 613-591-1922 Fax: 613-591-3485
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