As said by pm different Kenwood devices use different versions it depends on which files structure they have.
For example DNX7230DAB have a similar structure to nuvi 3xxx series and gets NTU maps and related additions.
Older devices having a structure similar to nuvi 1xxx series get NT map and few additions, probably no ASR etc.
There is not a rule to follow, must look at garmindevice.xml in Garmin folder:
All the supported files are listed along their paths and in red in .xml you can see Unicode map is supported by this kenwood device.Code:Please Login or Register to see the links
Old devices (before 2013) probably don't support NTU so use NT.
Be sure to have your Kenwood device latest firmware.
But wait for Kenwood experts for more info