It would be useful to be able to express the scripts used in the fields (especially name) and if it has been transliterated when its not in the script of the character set encoding of the message. This is important when services are using the returned identity claim and trying to connect them to existing records in their systems. This is more problematic when the claim data has been transliterated from its original language and the receiving system doesn't know that and is guessing.
For example both MÖLLER & MØLLER will be transliterated to MOELLER on a 9303 compliant MRZ. Its useful for the receiving party to know that if its getting MOELLER whether that is a natural script representation (i.e. the name is in fact MOELLER) or whether it needs to consider that the original script might be MÖLLER or MØLLER, which might have been stored as MOLLER in their system.