<?xml version="1.0" encoding="UTF-8"?>
<xs:schema 
targetNamespace="http://www.ruleml.org/0.86/xsd" 
xmlns="http://www.ruleml.org/0.86/xsd"
xmlns:xs="http://www.w3.org/2001/XMLSchema"
>

	<xs:annotation>
		<xs:documentation xml:lang="en">
			XML Schema for a 'UR'-Centered Binary Datalog RuleML sublanguage
			File: urcbindatalog.xsd
			Version: 0.86
			Last Modification: 2004-06-23
		</xs:documentation>
	</xs:annotation>
	

	<xs:redefine schemaLocation="urcdatalog.xsd">
		<!--
			make atoms binary so that atom's content model is:
			(
			  ( _opr, (_slot)*, (ind | var), (ind | var), (_slot)* ) |
			  ( (_slot)*, (ind | var), (ind | var), (_slot)*, _opr )
			)
		-->
		<xs:group name="atom.extend">
			<xs:sequence>
				<xs:choice minOccurs="2" maxOccurs="2">
					<xs:element ref="ind"/>
					<xs:element ref="var"/>
				</xs:choice>
			</xs:sequence>
		</xs:group>		
	</xs:redefine>
	
</xs:schema>