LBase: incorporating new section 3 from Pat

I consider this ready to go, and expect to make a publication request 
as soon as I get the (already requested) W3C Director's go-ahead.

http://www.w3.org/2001/sw/RDFCore/TR/NOTE-lbase-20030117/

I have replaced section 3 with updated material from Pat, fixing HTML and formatting 
bugs. Pat, can you confirm that pt 3 was the only bit you changed, since I have 
only copied that bit in from your last email'd snapshot. 

Dan