Gentlemen,
Thanks so much for your quick responses. Your suggestions have both been very helpful. I've got the solution now.
Using the Object Model browser allows me see all parameters/values. Using the brackets [] to denote a specific item in a list is the way to go.
I ran into a slight snag using them with curl:
7eb8a30b-88e2-409d-8777-501b142c9639-image.png
However, a StackOverflow post https://stackoverflow.com/questions/8333920/passing-a-url-with-brackets-to-curl about using brackets in curl solved the issue: pass in a -g flag to turn off the URL globbing parser https://curl.se/docs/manpage.html#-g.
Now it works perfectly:
77a3d400-f767-4a34-bbf4-31a1e28076c1-image.png
Thanks again for your help,
Mike