Exactly what do you expect to be able to accomplish with them?
I've always had the feeling that ARX is an elegant wrapper around something older. E.g. the ARX API's still doesn't provide methods for manipulating multilines segment omissions, still AutoCAD supports them. In early versions of ARX, lots of methods would return eNotImplementedYet ... which didn't effect AutoCAD's core functionality.
If you're looking for various graphic algorithms, I'd recommend that you start at Dave Eberly's site: http://www.geometrictools.com. There's also the graphics faq at http://www.faqs.org/faqs/graphics/algorithms-faq/
Best Regards,
Henrik Vallgren
www.streamspace.com