Object naming? and tree-based XML/HTML parsing

[Daniel Ringwalt]

I've picked up this much from the source code of gnustep-base:

1. Objects that are part of the OpenStep specification start with NS.
2. Additions to OpenStep, like Apple's event-driven XML parsing, start
with GS.
Please don't flame me about the above, I don't know if GNUstep or
Apple created this first.

What I don't understand are why there are duplicates like NSArray/
GSArray. GSArray seems to be larger and under more scrutiny, but then
why is NSArray and not GSArray the one used by other objects? What
sort of additions are there in GSArray, and why is NSArray still
there?

And are there any plans to implement Apple's tree-based XML parsing
(NSXMLNode, etc.)? How compatible is GSXMLParser to Apple's
NSXMLParser?