Random Finite Set - Notation

Greetings:

I am reading a paper whose topic is the application of random set theory to data fusion. I am encountering terminology that is not defined in the paper itself and is therefore probably "standard" set notation.

More specifically, the author talks about the use of "a multitarget multisensor model - a random set = **T(X) U C(X)**".

As far as I can tell, the meaning of these terms "T", "C", and "X", are not defined. Are these standard set theory terms?

You may need to know that I have a Bachelor's degree in engineering (from 30 + years ago). So while I do some math background, I am new to random sets, although I do believe I understand the basics of fuzzy logic, which appears, from other things I have read, to have a connection to random set.

Thanks in advance for any thoughts re the notation **T(X) U C(X)**