Instance patterns

Many XML instances, when viewed from the NVDL perspective, form patterns. An example is the layer cake or sandwich pattern, where elements from two schemas form a sandwich. XSLT wrapping XHTML is an example of such a pattern. In this pattern, The outer layer wraps N layers of the inner namespace. An XSLT stylesheet may be said to wrap many fragments of XHTML. Another such pattern is the foreign block inserted into another namespace. A block of SVG may be found in an XSL-FO document. RDF may be found in an XHTML header. MathML may be found in XHTML. Each of these uses represents a minority namespace usage within another namespaced document.