I enjoy random map scripting, and it's especially interesting to consider the possibilities that come with using object constants to generate hidden/beta/undocumented stuff.
Age of Empires II HD The Forgotten expansion adds a series of new RMS constants which were unfortunately not really documented.
I've done some testing and compiled a list of additional constants that were added with The Forgotten.
I've only included new constants that were not in The Conquerors, so if you are looking for all the old ones, take a look at this list
There are many new constants past 865 (where TC stopped) but also some constants that used to cause crashes or that used to code for dead heroes in the 1 to 865 range have been reassigned to working AOF objects.
This list should be complete as of patch 5.1
Future patches may add more content!
Feel free to send me corrections or updates/findings of your own!
Hope this is useful.
-Added units from the most recent patch
-Added everything from African Kingdoms
-Sheet 2 now shows everything grouped by type for easy reference
-Added everything from Rise of The Rajas
(only on sheet 1; I still need to add the Rajas stuff to the second sheet too)