XML Schema Complete Reference, The

16.1. Schema Validation and Schema Processing

For processing a document against a schema, the schema must normally first be built from one or more schema documents. The resulting (abstract) schema is described in Chapter 15. Also, the document to be processed against that schema must first be parsed and an information set for the (concrete) document built, as described in Section 2.2. At least this must appear to happen; as long as the results are correct, the internals of the processor are up to the processor writer.

The point, for the purposes of this chapter, is that schema processing is described in the Schema Recommendation as validation of abstract information items (which we call the “XML instance”) with respect to an abstract schema. ...