DNWithOctetString (also referred to as DN-Binary) is defined in an Internet Draft draft-armijo-ldap-syntax-00 for Microsoft Active Directory LDAPSyntaxes with an OID of 1.2.840.113556.1.4.903
DNWithOctetString: 1.2.840.113556.1.4.903
        Encoded as a :
        DNWithOctetString  = OctetTag ':' Count ':' OctetString ':' DN
        OctetTag = 'B' | 'b'
        Count = positive decimal number, counting number of encoded characters
                in OctetString
        OctetString = [EncodedByte]*  // Note: the number of characters in the
                string encoding of the OctetString is Count.
        EncodedByte = [0-9 | a-f | A-F] [0-9 | a-f | A-F]
        DN = <normal string encoding of a DN>

        As an example, the string encoding of the combination of 0x74 0x65 0x73
        0x74 and DC=Microsoft,DC=Com is

        B:8:74657374:DC=Microsoft,DC=Com for a DN with binary (a.k.a. DN with octetString) or A Distinguished Name plus a binary large object.

More Information#

There might be more information for this subject on one of the following: