This extensions performs is a language service extension for XML files which uses XSD schema definition to perform validation of the xml in real time as you edit xml files.
Xml Validator uses the XSD annotations to perform schema validation.
To associate the XSD with your xml file you need to include the xmlns:xsi namespace and either add an xsi:noNamespaceSchemaLocation or xsi:schemaLocation attribute which gives the xsd which defines your schema.
Here is an example of noNamespaceSchema attribute
<?xml version="1.0" encoding="UTF-8"?>
<invoice
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:noNamespaceSchemaLocation="invoice.xsd">
Or in this example associating that prefix tns and namespace http://invoice is defined in an xsd named invoice.xsd.
<?xml version="1.0" encoding="UTF-8"?>
<tns:invoice
xmlns:tns="http://invoice"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://invoice invoice.xsd ">
You can specify multiple namespaces in a row in one attribute like this:
<tns:invoice
xsi:schemaLocation="http://uri1 uri1.xsd http://uri2 uri2.xsd http://uri3 uri3.xsd"
This extension requires .NET Core to be installed.