ues-attributes2/entity-resolver2/locator2 read-only?

Consider the use-attributes2, use-locator2, and use-entity-resolver-2 
features in SAX 2.0.1. Are these:

1. Read-only?
2. Read-write?
3. Read-only or read-write depending on the parser?

The docs don't say. This should be clarified.
-- 

   Elliotte Rusty Harold
   
   Effective XML (Addison-Wesley, 2003)
   http://www.cafeconleche.org/books/effectivexml
   http://www.amazon.com/exec/obidos/ISBN%3D0321150406/ref%3Dnosim/cafeaulaitA