The validator for DFDL isn't checking referential integrity of type references to type definitions.

We have many test examples with this issue:

<schema xmlns="http://www.ogf.org/dfdl/dfdl-1.0/XMLSchemaSubset"
targetNamespace="http://example.com">
<element name="foo" type="bar"/><!-- Illegal: no prefix on name of the type. -->
<complexType name="bar">
<sequence/>
</complexType>
</schema>

You can't write a schema with xml schema as the no-prefix namespace, and then not qualify
the type references (or element or group references, or references to dfdl:defineFormats, or escapeSchemes, or variables, or...)
without qualifying them.

This bug report is that the validator is not catching these.

Either we turn on some obscure feature of Xerces and it will test and catch these, or we should use either XSOM or the Apache XML Schema library as a secondary validator.

(a separate bug report will describe the test schemas being illegal and needing to be fixed.)