XOM API for Processing XML with Java

[Elliotte Harold <elharo AT metalab.unc.edu>]

A recent erratum to the XML Base spec states:

The base URI of an element bearing an |xml:base| attribute with a value 
that is not a valid URI reference is application dependent.

In this context, XOM is an application, and can do whatever it wants to 
in this case.
The question is what it should do.  For example, consider this document:

<element xml:base="http://www.example.com/test/%GF.html"/>

What is the base URI of the element? Here are the possibilities I've 
thought of:

1. Return null (what XOM is doing now)
2. Return the value of the xml:base attribute untouched and unresolved.
3. Return the empty string

Any other ideas?

Related question:

Element root = new Element("root");
Document doc = new Document(root);

What should doc.getBaseURI() and root.getBaseURI() return? Currently 
null is being returned. However
according to RFC 2396:

  A URI reference that does not contain a URI is a reference to the
  current document.  In other words, an empty URI reference within a
  document is interpreted as a reference to the start of that document,
  and a reference containing only a fragment identifier is a reference
  to the identified fragment of that document.


Thus perhaps it makes sense here to return the empty string here instead 
of null? That would also avoid some possible unexpected 
NullPointerExceptions if a client forgot to do a null check.

--
Elliotte Rusty Harold