Summary of API?

[Tim Bunce]

Would someone do me the great favour of summarizing some things for me?

Just the Goals and Design Principles would be great, an outline of
the API(s) would be a bonus.

I'm particularly interested in:
        Basic object API (there is going to be an object right?)
        Extensibility (through subclasses or in other ways)
        Using the extensibility well to avoid bloat of the basic object
        Efficiency for common usage

Thanks.

Tim.

p.s. Yes, I've looked at the archives.