Overview#Binary Encoding Option defined in RFC 4522 document defines an attribute option, the binary option, which can be used in an attribute description RFC 4512 in an LDAP operation to specify that the associated attribute values or assertion values are, or are requested to be, encoded according to the Basic Encoding Rules (BER) BER as used by X.500 X.500 directories, instead of the usual LDAP-specific encoding.
The binary option was originally defined in RFC 2251. The LDAP technical specification RFC 4510 has obsoleted the previously defined LDAP technical specification RFC 3377, which included RFC 2251. The binary option was not included in the revised LDAP technical specification for a variety of reasons including implementation inconsistencies. No attempt is made here to resolve the known inconsistencies.
In terms of the protocol RFC 4511, the binary option specifies that the contents octets of the associated AttributeValue or AssertionValue OCTET STRING are a complete BER encoding of the relevant value.