Where to find a list of acceptable types for TraceEvent messages

I am using

UNICODE_STRING FileName;

and want to print out the contents of the associated buffer to make sure the translation with RtlInitUnicodeString(&FileName, pJtagFile->FileName);

worked properly [my data supplied in FileName is in the new FileName.Buffer]. WCHAR is the type. I know the basic ones ... Hex and so forth but haven't figured out the WCHAR type for the TraceEvents string.

Looked all over and MS doesn't seem to have this published. Perhaps I am blind...