Freshservice Portal Documentation

I have been struggling to find any decent information on Freshservice portal placeholders, and was wondering if anyone knew anything about them, or where I could look to find them.

For example:

{{ portal.service_catalog_items_url }}

Is a placeholder that I can’t seem to find in documentation anywhere (I’ve gone over every support article that I can find without success), and yet it seems to exist anyways (discovered after 5 minutes of guesswork). This hasn’t been a huge issue up until now, but as I have been trying to do more complicated things with the interface, trying to guess what the placeholders are is starting to get difficult.

Any help would be greatly appreciated.