When defining a material's Thermal properties, one can see that temperature is always defined with the decimal unit prefix, dK (deciKelvin) but also dC and dF, see attached screenshot. This is not conventional, and was enough reason for suspicion.
I then compared some values with that of existing library materials (e.g. that of Thermal Conductivity and Specific Heat), and all values seemed to be approximately/exactly a factor 10 times higher than what they should be... Hmm, interesting, so maybe d does not actually stand for deci... Would it be degrees instead? That would make sense for degrees Celsius and degrees Fahrenheit, but there is no such a thing as degrees Kelvin, so this is unlikely.
Any confirmation would be very welcome, and removal of the d in any future version is highly recommended, as it easily leads to confusion and in unlucky cases to catastrophy.
EDIT: I just noticed that the unit of the field "Temperature (TREF)" in above screenshot just lists C instead of dC (and in its corresponding drop-down menu all other units (K,F,R) also don't have any prefix). This makes things even more confusing.
As the NX expressions guy, I'm pretty sure this is an attempt to distinguish between an absolute temperature and a temperature change. There are some subtleties to the underlying math that we humans automatically process when we do the math by hand, but that the computer needs some clarification on to keep things straight.
The CAE team may help clarify this specific instance for you.
In the expressions dialog, we display these like this:
But if you export these expressions to a text file, you'll see this style, which looks more like your image:
Does that help?