invalidAttributeSyntax error when an empty string is added

Hi,

When I tried to add an empty string to the IA5 String attribute, slapd returned invalidAttributeSyntax(21) error. Is this a correct behavior?

from RFC4517:

=== 3.3.6. Directory String

A value of the Directory String syntax is a string of one or more arbitrary characters from the Universal Character Set (UCS) [UCS]...

[...]

3.3.15. IA5 String

A value of the IA5 String syntax is a string of zero, one, or more characters from International Alphabet 5 (IA5) [T.50], ... ===

It seems that zero-length IA5 String is allowed, while Directory String have to be one or more characters. (However, I don't understand why zero-length Directory String is not allowed. It is very frustrated.)

I'm using OpenLDAP 2.3.27.

Regards,

-- Kazu Nisimura