Section 23.2.2 says:
In a TEI-conformant document, it is assumed that all attributes not explicitly labelled with a namespace (such as, for example xml:id) also belong to the TEI namespace, and are defined by the TEI.
This implies that any other modification (including a renaming or reversible modification) must either specify a different namespace or specify no namespace at all.
Does "no namespace at all" mean using
? I assumed it meant not using @ns on the element, but that would contradict the first paragraph. It would be good to clarify this.
Later in this section, the Guidelines say, "Similar methods may be used if a modification (clean or unclean) is made to the content model or some other aspect of an element, or if it declares a new element."
The following are unclear:
a) Similar methods to what? Are we just talking about use of @ns?
b) In what case(s) would you define a new namespace for a clean customization of an element? As far as I can tell from the discussion in chapter 23, you never declare a new namespace for a clean customization.