RM already has a section for notes to attach to a rule, but for more complex rules, it would be nice to insert a comment inline. Would it be possible to add an "action" to rule machine that was a no-op, and would allow you to insert text in that line?
E.g., action name: comment.
Field to fill in: comment text.
This has come up a few times in the past. Here is a recent response:
Or, tl;dr, if you really want this: log to either a real or virtual device (you don't have to do anything with that virtual device) or use the "Notes" section, since this isn't likely to happen.