New in Oracle Directory Server Enterprise Edition 11g Release 1 (11.1.1).
LDAP's RFC 4511 states that an "and" filter choice evaluates to TRUE if all its constituent (SET OF) filters evaluate to TRUE. In practice, the result for an "and" filter choice is the set of entries that match each and every constituent filter applied on its own.
In previous versions of Directory Server, filters of the form (&(attr>=v1)(attr<=v2)) were interpreted as entries with values in the range v1...v2. This interpretation is too restrictive when the attribute is multi-valued, because an entry might have values that match both constituent filters but the values themselves might be smaller than v1 and bigger than v2.
The Directory Server now implements the RFC 4511 behavior by default, unless compat-flag is set to no-rfc4511.