@xml:base with @rendition (and maybe other pointers)

@rendition has datatype teidata.pointer. Pointers can point to locations 
either within the current document or elsewhere. They should be expanded 
with any @xml:base attributes up the XML tree.

But @rendition is supposed to point to an element in the tagsDecl 
element, normally within the same document, though presumably it could 
be the tagsDecl in some other document.

My question: Is it really the case that a rendition pointer should honor 
parent @xml:base attributes?

I guess the theoretical answer is yes, but I can imagine cases where the 
@xml:base attributes are primarily for setting image paths, .xml 
directories, and http addresses, and the coder does not really intend 
the @rendition attributes to point externally.

Thoughts?

John