Measuring point with characteristic of data type "CHAR"

Hello,

I would like to create a characteristic for a measuring point, where I can indicate in the measuring document that the measurement reading is either "yes" or "no".

As far as I see, data type "CHAR" should be used for this in the characteristic. However, only "NUM" can be used for measuring points.

Please let me know how to fix this. I read something about using the valuation code for this, but how do you link the valuation code to the measurement reading?

Regards,