XML Schema (XSD) self-validation — judge the statement: “You can validate an XML Schema document against its schema, just as you would any other XML document.” Indicate whether this claim is correct or incorrect.

Introduction / Context:
XML Schema Definition (XSD) is itself an XML vocabulary with a normative schema (often called the “XML Schema for XML Schemas”). Because XSD documents are XML, they can be validated like other XML instances—by referencing the appropriate schema and using a validating parser. This question probes whether you know that schemas can themselves be validated.

Given Data / Assumptions:

• An XSD file is a well-formed XML document using the XML Schema namespace.
• A published schema document defines the structure of conforming XSDs.
• Validation requires a validator that recognizes XML Schema 1.0/1.1 as implemented by the tool in use.

Concept / Approach:
Since XSDs are XML, standard validation mechanics apply: associate the schema-for-schemas via xsi:schemaLocation or validator configuration, then run validation. Many editors and build tools (e.g., IDEs, xmllint with appropriate flags, Xerces, Saxon) can validate an XSD against the W3C’s schema for schemas. This is analogous to validating any XML instance against its XSD, with the difference that the “instance” happens to also be a schema.

Step-by-Step Solution:

Verification / Alternative check:
Most validators report meaningful diagnostics when an XSD misuses constructs (e.g., conflicting type definitions), demonstrating that schema documents are validated like any XML data instance.

Why Other Options Are Wrong:

• “Incorrect” is false—toolchains routinely validate XSDs.
• “Valid only for DTD/RELAX NG” confuses alternative schema languages with XSD’s capabilities.
• “Depends on SAX vendor” is irrelevant; validation is a layer above event parsing.

Common Pitfalls:
Thinking schemas are special and cannot be validated; mixing up well-formedness checking with schema validation; assuming all validators support XML Schema 1.1 if you use 1.1 features.

Final Answer:
Correct