OR-Name is a Microsoft Active Directory LDAPSyntaxes defined in Draft-armijo-ldap-syntax-00 with an OID of 1.2.840.113556.1.4.1221

Ldapwiki also found where it is referred to as CaseIgnoreString[1]

OR-Name is also defined as an OID of

OR-Name: 1.2.840.113556.1.4.1221
        Encoded as:
        ORName = DN | "X400:" ORaddress "#X500:" DN | "X400:"ORaddress
        DN = normally encoded rfc 1779 name
        ORaddress = some string encoding for OR addresses.
Note that an unescaped # character must not be legal in this encoding.
This is necessary to be able to identify where the #X500 starts if the middle choice of the encoding is chosen.

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