I have a question about a passage in section 5.1 of the XML standard that I can’t quite wrap my head around:

Non-validating processors are required to check only the document entity, including the entire internal DTD subset, for well-formedness. [Definition: While they are not required to check the document for validity, they are required to process all the declarations they read in the internal DTD subset and in any parameter entity that they read, up to the first reference to a parameter entity that they do not read; that is to say, they must use the information in those declarations to normalize attribute values, include the replacement text of internal entities, and supply default attribute values.] Except when standalone="yes", they must not process entity declarations or attribute-list declarations encountered after a reference to a parameter entity that is not read, since the entity may have contained overriding declarations; when standalone="yes", processors must process these declarations.

The phrase "and in any parameter entity that they read” is what is puzzling me.  How can I, as a non-validating processor, have a parameter entity that I have read?  Section 2.9, for example, it is said that non-validating processors are not required to read parameter entities of any sort (internal or external).

The only way I can make sense of that paragraph is to interpret it as saying:

“…[non-validating processors] are required to process all the declarations they read in the internal DTD up to the first parameter entity reference. However, if a non-validating processor goes beyond the minimum required behavior and instead reads and processes the contents of some parameter entities, then it should stop processing the internal DTD at the point it encounters a reference to a parameter entity that it chose not to read (and process).”

Is there some other interpretation of this that I’m missing? Or is that what most folks think this is saying?

David