I see that there are a lot of controls in Kentico, but not all of them are documented here on devnet. Why not?

CMSBaseDataSource, not documented?
CMSQueryDataSource, not documented?
CustomTableDataSource, not documented?

While we are on the subject of controls and documentation: why are there 4 control assemblies and what is the difference between them?

CMS.Controls
CMS.ExtendedControls
CMS.UIControls
CMS.FormControls

And, last question: why do some controls have the CMS prefix? For example, in the CMS.Controls assembly, there is DataPager and CMSDataList controls. Why does the second have a CMS prefix, and the first not?

Thanks for your attention!