4.3.5, first line reads:

• • • • • 
          This type defines the content of a component. Content Specifications SHALL declare either a String attribute "href" that references the content or a String attribute "data" whose value is the data or, but not both. [PDP-25] It has the following, general representation:

The general representation is misleading. Or at least I think it is.

It implies href: URI or data: string.

But, from 4.3.3.2 content, we learn it should be:

content: href or

content: data

Yes? True they are both holders for particular types but given the overlap of model and syntax, it is rather confusing.

Assuming that makes sense, suggest something like:

The ContentSpecification type has one of two, mutually exclusive, values: href or data.

BTW, I would not mix type discussions with nodes. Too easy to slip from one to another.