T.61 strings and control characters

The December 1991 Stable Implementation Agreements for Directory
Services Protocols states:

               a)   Alphabets: T.61 Strings used  as attribute values shall
               only  encode graphic characters  and spaces. They  shall not
               contain formatting  characters (such as subscript)  or other
               control characters;

Does any know if this means that T.61 Strings shall not contain escape
characters? Then T.61 Strings would therefore be limited to ASCII with
accents. Switching to Japanese, Greek, etc. requires an escape.

-- Burt