XML Schema: Component Designators WD

This is an interesting one:

The XML Schema Working Group has released a revised Working Draft of XML Schema: Component Designators. The document defines a scheme for identifying the XML Schema components specified by the XML Schema Recommendation Part 1 and Part 2.

The idea is to be able to address components of an XML Schema, just as we can address parts of an XML document by XPath or XPointer. An absolute schema component designator syntactically is an URI, whose main part is an URI of a schema document and fragment identifier is XPointer pointer conforming to the new proposed xscd() XPointer scheme. The syntax is obviously XPath-like.

Potential addressable XML Schema components are:
{type definitions}
{attribute declarations}
{element declarations}
{attribute group definitions}
{model group definitions}
{notation declarations}
{identity constraint definitions}
{facets}
{fundamental facets}
{member type definitions}
{attribute uses}
{particles}
{annotations}
etc.

Examples:
schema-URI#xscd(/type(purchaseOrderType))
schema-URI#xscd(/type(Items)/item/productName)
or even schema-URI#xscd(/type(Items)/item/quantity/type()/facet(maxExclusive)).

Good idea, isn't it? Obviously the core question is - why not just use XPath, the schema is just XML document after all? Actually looks like they are uncomparable things. AFAIK it's also one of first (after XInclude of course) real applications of XPointer.