XML format
XML Schema (XSD)
The dominant XML schema language: namespace-aware, richly typed, and itself written in XML.
An XSD describes what a valid document looks like — its elements, their order, cardinality and datatypes. Because a schema is itself an XML document, schemas can be searched, diffed and version-tracked with the same tooling as the payloads they govern.
Well-formedness and validity are different questions. A document can parse perfectly and still violate its schema, which is why the workspace treats validation as a separate step from ingestion.
Constraints that bite
- targetNamespace on the schema is what instance documents must declare; omitting it means no-namespace.
- xsi:schemaLocation in an instance is a hint most validators ignore unless configured.
- <xs:sequence> is order-sensitive; reordering valid elements can invalidate a document.
- Imports and includes may resolve over the network — a real supply-chain consideration when validating untrusted schemas.
- A schema-valid document can still be rejected by a profile layered on top (Peppol, ISO 20022 usage rules).
- Root element
<schema>- Media type
application/xml- Extensions
.xsd- Namespaces
http://www.w3.org/2001/XMLSchema
- XMLDir label
xml
Specification: W3C XML Schema
A minimal valid document
Every example on this site is checked against the same parser the workspace uses, so what you see below is known to be well-formed.
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"
targetNamespace="https://example.com/orders"
elementFormDefault="qualified">
<xs:element name="Order">
<xs:complexType>
<xs:sequence>
<xs:element name="OrderId" type="xs:integer"/>
</xs:sequence>
</xs:complexType>
</xs:element>
</xs:schema>Namespaces you will meet
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