- Form Summaries - New in Ubercart 2.x! Extends the core Drupal Forms API to automatically build form summaries used on configuration overview pages. Modules adding settings forms or altering core settings forms can get their data displayed in these summaries without any core hacking.
- TAPIr (Tables API) - Updated in Ubercart 2.x. Defines tables in a way that allows them to be altered and extended by other modules.
There are several core systems in Ubercart that are used internally and meant to be used by third party developers to extend functionality like form summaries. While this is not a comprehensive guide to the core systems of Ubercart, it documents parts of the API that demand a full explanation and in-depth documentation.