The main source of Halo 3:ODST Speedruns is Haloruns.com.

The SRC page acts as a site to track non HR.com categories because it is quick and easy to change. It also keeps the HR.com focused on the 'main' categories to encourage competition and optimisation.

The SRC page may change over time as the popularity of categories changes. There will need to be a balance of having fun 'side' categories but not too many excess side categories.

If you are interested in having a particular category added feel free to create a new thread in this form asking for it to be added. You can also ask in the Haloruns.com Discord linked on this page.