In Finale it was possible to insert special text ‘fields’ into the score. E.g.
File date effectively timestamps any PDF’s that get created. (Much simplifies tracking revisions of pdf scores.)
I have not yet found how to do this in Dorico (searching help PDF for “duration” gets 1,149 hits 
)- What are the equivalent keywords Dorico?
Dorico calls them tokens.
They can be used in text frames (just right click in a text frame and a menu appears with all possible tokens). Much of the content for tokens comes from the Project Information dialogue (ctrl-I)
Dorico calls the fields “tokens”. You can easily add them to a text frame by right-clicking inside the frame.
Alternatively, they follow a syntax, using something like {@projectTitle@}
There are tokens for the Time/date stamp, number of pages, total duration, and the Filepath or name.
Thank you (all) for your quick & comprehensive answers.
One of Dorico’s strengths is definitely this forum! 
