This is actually documented in a fairly straightforward way in section 12.20 of the documentation – as long as you know to look at that section. Which I guess I would’ve done by searching the documentation for “current action.” Searching through the documentation can be a pain (it bugs me that it slowly constructs the list of hits backwards, working through all the examples before it gets to the main text that I’m actually looking for), but I often have reasonably decent luck finding what I’m looking for – though it can take a few tries to construct the right query.
(I wonder if you’re thinking of this – “convert to request” doesn’t seem to be documented, and is one of those bits of I6 voodoo anyway. In related news, I haven’t worked on this for a while because I’m not sure how to extract “kissing iris” from “asking folks to try kissing Iris.”)