Strange code on Me 110

[DB601E]

Hi,

i have a strange code for a Me 110 of KG2:
In the NVM for a missing crew member i found the code for the
aircraft:

T-ZH

This seems strange to me, as the "normal" format is almost always XX+XX
(so 4 digits)

Does anybody know a marking/code like this?

Background info: This aircraft was used for training crews as preparation for the Me 410 training. Unit was 15./KG 2 (Destroyer group)

Thanks for help