4.2 Location-source/Base address

4.2.a Should we formalize at all the concept of a base address? 

4.2.b If so, should we call it a location source or something else? 

4.2.c Should we formalize the concept of the implied location source? 

4.2.d If so, should the values be DOCELEM and REFERRER, defaulting to 
DOCELEM?

Cheers, Tim Bray
tbray@textuality.com http://www.textuality.com/ +1-604-708-9592