This document briefly compares XML Schema's 42 elements with RELAX NG's 28 elements. In the table that follows, the first column lists all the XML Schema elements while the second column lists any RELAX NG elements that have a one-to-one relationship, a comparable purpose, or only a roughly similar purpose to XML Schema elements. Elements unique to each language are also listed in separate tables.

1. XML Schema and RELAX NG
Element Comparison
Michael Fitzgerald
http://www.overduebooks.net
This document briefly compares XML Schema’s 42 elements with RELAX NG’s 28 elements. In the table
that follows, the first column lists all the XML Schema elements while the second column lists any
RELAX NG elements that have a one-to-one relationship, a comparable purpose, or only a roughly similar
purpose to XML Schema elements. Elements unique to each language are also listed in separate tables
below.
The prefixes in the tables, xs:, rng:, and a:, are associated with the following namespaces:
• xs: with http://www.w3.org/2001/XMLSchema
• rng: with http://relaxng.org/ns/structure/1.0
• a: with http://relaxng.org/ns/compatibility/annotations/1.0
XML Schema Element RELAX NG Element
xs:all rng:interleave, rng:optional
xs:annotation a:documentation
xs:any rng:anyName, rng:nsName
xs:anyAttribute rng:anyName, rng:nsName
xs:appInfo a:documentation
xs:attribute rng:attribute
xs:attributeGroup rng:define
xs:choice rng:choice
xs:complexContent
xs:complexType rng:element, rng:define, rng:ref
xs:documentation a:documentation
xs:element rng:element
xs:enumeration rng:choice, rng:value
xs:extension rng:param
xs:field
xs:fractionDigits rng:param
xs:group rng:group, rng:div
xs:import rng:externalRef, rng:parentRef
xs:include rng:include, rng:externalRef
xs:key
xs:keyref
xs:length rng:param
xs:list rng:list
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2. xs:maxExclusive rng:param
xs:maxInclusive rng:param
xs:maxLength rng:param
xs:minExclusive rng:param
xs:minInclusive rng:param
xs:minLength rng:param
xs:notation
xs:pattern rng:param
xs:redefine rng:include, rng:define
xs:restriction rng:except, rng:notAllowed
xs:schema rng:grammar
xs:selector
xs:sequence
xs:simpleContent
xs:simpleType
xs:totalDigits rng:param
xs:union rng:list
xs:unique
xs:whiteSpace rng:param
XML Schema Unique Elements
The following table lists XML Schema elements for which there is no similar or equivalent RELAX NG
element (first column) followed by an explanation why (second column).
XML Schema Element Explanation
xs:complexContent Not necessary in RELAX NG syntax
xs:field RELAX NG does not implement keys
xs:key RELAX NG does not implement keys
xs:keyref RELAX NG does not implement keys
xs:notation RELAX NG does not directly support notations
xs:selector RELAX NG does not implement keys
xs:sequence Not necessary in RELAX NG syntax
xs:simpleContent Not necessary in RELAX NG syntax
xs:simpleType RELAX NG uses external datatype libraries; types are external
xs:unique RELAX NG does not implement keys
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3. RELAX NG Unique Elements
The following tables lists RELAX NG elements for which there is no equivalent or similar XML Schema
element (first column) followed by an explanation why (second column).
RELAX NG Element Explanation
rng:data Uses the xs:type attribute
rng:empty Uses the xs:complexType element
rng:interleave XML Schema requires deterministic content models
rng:mixed Uses with xs:mixed attribute
Achieved with xs:minOccurs="1" and
rng:oneOrMore
xs:maxOccurs="unbounded"
Achieved with xs:minOccurs="0" and
rng:optional
xs:maxOccurs="1"
rng:param Uses facet elements (xs:maxLength, xs:minLength, etc.
rng:ref Achieved with the xs:ref attribute
rng:start Uses global xs:element declaration
rng:text Achieved with xs:type="xsd:string" attribute
rng:value Achieved with xs:value attribute
Achieved with xs:minOccurs="0" and
rng:zeroOrMore
xs:maxOccurs="unbounded"
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