Share via


XML Document Validation

Note

This article applies to Visual Studio 2015. If you're looking for the latest Visual Studio documentation, see Visual Studio documentation. We recommend upgrading to the latest version of Visual Studio. Download it here

The XML Editor checks XML 1.0 syntax and also performs data validation as you type. The editor can validate using a document type definition (DTD) or a schema. Red wavy underlines highlight any XML 1.0 well-formed errors. Blue wavy underlines show semantic errors based on DTD or schema validation. Each error has an associated entry in the error list. You can also view the error message by pausing the mouse over the wavy underline.

Schemas used in validation are found by matching the targetNamespace of a compiled schema with the element's xmlns declaration. Compiled schemas are loaded from one of the following locations, listed in order of priority:

  • From the file name specified in the Schemas field of the document Properties window.

  • An inline schema or DTD.

  • An external DTD or an xsd:schemaLocation and xsd:noNamespaceSchemaLocation attribute

  • An "x-schema" XDR schema namespace URI.

    Schemas can also be found in the following additional locations when the schema has a non-empty target namespace:

  • Another editor window that contains the schema.

  • A schema in the current solution.

  • A schema from the schema cache directory.

XSLT Files

When editing an XSLT file, the xslt.xsd file located in the schema cache is used for validation. Validation errors are shown as blue wavy underlines. Errors from the XSLT compiler are shown as red wavy underlines.

XML Schema (XSD) Files

When editing an XML Schema file, the xsdschema.xsd file located in the schema cache is used for validation. Validation errors are shown as blue wavy underlines. Any compilation errors are also shown with red wavy underlines.

See Also

XML Editor