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XML Schema (XSD)

<xs:element>

Declares an element's name, type, occurrence range, defaulting, and whether an explicit xsi:nil is allowed.

A global element is reusable and may be an instance root. A local declaration appears in a content model and can carry minOccurs and maxOccurs.

Use either a type attribute or one anonymous simpleType or complexType child. nillable and optional solve different problems: explicit nil versus presence.

Format
XML Schema (XSD)
Namespace
XML Schema Definition (XSD)
Parent
<xs:schema><xs:sequence><xs:choice>
How many
Any number globally or within a model group.

What it contains

Attributes

  • nameoptionalRequired for a declaration unless ref points to a global element.
  • typeoptionalA QName naming the type when no anonymous type child is present.

Cardinality and constraints

Any number globally or within a model group.

  • name and ref are mutually exclusive.
  • minOccurs and maxOccurs apply only to local particles.

What our validator does

The XML validator checks well-formedness and selected SOAP or XML Schema vocabulary rules. It reports this content-model defect with a concrete repair while staying silent on rules it cannot establish from one document.

Broken and fixed

Both documents below are well-formed XML — that is the point of this corpus — and both are run through the validator on every test run. The verdicts here are what it returned, not what we expect it to.

broken
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" targetNamespace="urn:example:catalog">
  <xs:complexType name="Product"><xs:attribute name="active" type="xs:boolean" maxOccurs="2"/></xs:complexType>
</xs:schema>
xs:attribute cannot use minOccurs or maxOccurs; attributes use the use attribute instead.
fixed
<?xml version="1.0" encoding="UTF-8"?>
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:tns="urn:example:catalog" targetNamespace="urn:example:catalog" elementFormDefault="qualified">
  <xs:simpleType name="Sku"><xs:restriction base="xs:string"><xs:minLength value="1"/></xs:restriction></xs:simpleType>
  <xs:complexType name="Product"><xs:sequence><xs:element name="sku" type="tns:Sku"/></xs:sequence><xs:attribute name="active" type="xs:boolean"/></xs:complexType>
  <xs:element name="product" type="tns:Product"/>
</xs:schema>
No errors. Warnings may remain — a conforming feed can still be missing a self link — but nothing here is wrong.

Where it reaches

Related elements

All 49 elements

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