XML Document Validation
For the latest documentation on Visual Studio 2017 RC, see Visual Studio 2017 RC Documentation.
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
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.
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.
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.