I think there is a minor in-site documentation problem in the latest Phabricator when you create an Herald rule of type Object:
Choose the object this rule will act on (for example, enter rX to act on the rX repository, or #project to act on a project).
If you follow the documentation and you type
r1 (lowercase) it does not work:
No object exists by that name.
Playing a bit I figured out that I have to type
R1 (uppercase) so I think this is just a documentation problem
The string is defined in