DFC
However, the R/T manual tries to use generic catch all calls whenever possible......after all as a pilot on handover has no way of knowing that the controller's SSR failed 2 minutes ago.
If you've been handed over the SSR failure won't matter - we'll already have the ident on primary
But to verify what others have said - we're not interested in your heading when you're a transit and you're just giving us your details after you've just 'freecalled' the unit (the "pass your message reply").
The only time I need it is when I start vectoring you for an approach or separating you (Radar Advisory) - in which case it's normally "Turn left 10/20/30 degrees and report your new heading". Any headings we give you after that are based on the previous, but now known heading.