<!-- this 0.9.7 version is currently under voting by buildingSMART Standards Committee. When approved (expected June/July 2024) this will be renamed to 1.0 without changes -->
<xs:schema xmlns:ids="http://standards.buildingsmart.org/IDS" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:altova="http://www.altova.com/xml-schema-extensions" targetNamespace="http://standards.buildingsmart.org/IDS" elementFormDefault="qualified" attributeFormDefault="unqualified" version="0.9.7">
	<xs:import namespace="http://www.w3.org/XML/1998/namespace" schemaLocation="http://www.w3.org/2001/xml.xsd"/>
	<xs:import namespace="http://www.w3.org/2001/XMLSchema" schemaLocation="http://www.w3.org/2001/XMLSchema.xsd"/>
	<xs:import namespace="http://www.w3.org/2001/XMLSchema-instance" schemaLocation="http://www.w3.org/2001/XMLSchema-instance"/>
	<xs:element name="ids">
		<xs:complexType>
			<xs:sequence>
				<xs:element name="info">
					<xs:complexType>
						<xs:sequence>
							<xs:element name="title" type="xs:string"/>
							<xs:element name="copyright" type="xs:string" minOccurs="0"/>
							<xs:element name="version" type="xs:string" minOccurs="0"/>
							<xs:element name="description" type="xs:string" minOccurs="0"/>
							<xs:element name="author" minOccurs="0">
								<xs:simpleType>
									<xs:restriction base="xs:string">
										<xs:pattern value="[^@]+@[^\.]+\..+"/>
									</xs:restriction>
								</xs:simpleType>
							</xs:element>
							<xs:element name="date" type="xs:date" minOccurs="0"/>
							<xs:element name="purpose" type="xs:string" minOccurs="0"/>
							<xs:element name="milestone" type="xs:string" minOccurs="0"/>
						</xs:sequence>
					</xs:complexType>
				</xs:element>
				<xs:element name="specifications" type="ids:specificationsType"/>
			</xs:sequence>
		</xs:complexType>
	</xs:element>
	<xs:complexType name="entityType">
		<xs:sequence>
			<xs:element name="name" type="ids:idsValue"/>
			<xs:element name="predefinedType" type="ids:idsValue" minOccurs="0"/>
		</xs:sequence>
	</xs:complexType>
	<xs:complexType name="idsValue">
		<xs:choice minOccurs="1">
			<!-- place for potential additional rules for idsValue -->
			<xs:element name="simpleValue" type="xs:string" minOccurs="1" maxOccurs="1"/>
			<xs:element ref="xs:restriction" minOccurs="1" maxOccurs="1"/>
		</xs:choice>
	</xs:complexType>
	<xs:complexType name="classificationType">
		<xs:sequence>
			<xs:element name="value" type="ids:idsValue" minOccurs="0"/>
			<xs:element name="system" type="ids:idsValue" minOccurs="1"/>
		</xs:sequence>
	</xs:complexType>
	<xs:complexType name="partOfType">
		<xs:sequence>
			<xs:element name="entity" type="ids:entityType" minOccurs="1"/>
		</xs:sequence>
		<xs:attribute name="relation" type="ids:relations" use="optional" />
	</xs:complexType>
	<xs:complexType name="applicabilityType">
		<xs:sequence>
			<xs:element name="entity" type="ids:entityType" minOccurs="0"/>
			<xs:element name="partOf" type="ids:partOfType" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="classification" type="ids:classificationType" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="attribute" type="ids:attributeType" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="property" type="ids:propertyType" minOccurs="0" maxOccurs="unbounded"/>
			<xs:element name="material" type="ids:materialType" minOccurs="0" maxOccurs="unbounded"/>
		</xs:sequence>
		<!-- Please note there is an implementation agreement on the use of minOccurs and maxOccurs.
			Valid values are: 
			a. 0 to unbounded, meaning Optional
			b. 1 to unbounded, meaning Required
			c. 0 to 0, meaning Prohibited
		 -->
		<xs:attributeGroup ref="xs:occurs"/>
	</xs:complexType>
	<xs:complexType name="propertyType">
		<xs:sequence>
			<xs:element name="propertySet" type="ids:idsValue"/>
			<xs:element name="baseName" type="ids:idsValue">
				<xs:annotation>
					<xs:documentation>
						the moniker 'baseName' is chosen to clarify that the data needs to reference the property name as stored in the IFC file, 
						which might differ from the multiple language-dependent presentations (e.g. 'FireRating' vs. 'Fire rating').
					</xs:documentation>
				</xs:annotation>
			</xs:element>
			<xs:element name="value" type="ids:idsValue" minOccurs="0">
				<xs:annotation>
					<xs:documentation>
						Depending on the dataType attribute, values are expressed in the default unit documented at 
						https://github.com/buildingSMART/IDS/blob/master/Documentation/units.md, and unit conversion might be required.
					</xs:documentation>
				</xs:annotation>
			</xs:element>
		</xs:sequence>
		<xs:attribute name="dataType" type="ids:upperCaseName" use="optional">
			<xs:annotation>
				<xs:documentation>This is the name of an IFC Defined Type, all uppercase.</xs:documentation>
			</xs:annotation>
		</xs:attribute>
	</xs:complexType>
	<xs:complexType name="attributeType">
		<xs:sequence>
			<xs:element name="name" type="ids:idsValue"/>
			<xs:element name="value" type="ids:idsValue" minOccurs="0">
				<xs:annotation>
					<xs:documentation>
						Depending on the IFC type of the attribute, values are expressed in the default unit documented at 
						https://github.com/buildingSMART/IDS/blob/master/Documentation/units.md, and unit conversion might be required.
					</xs:documentation>
				</xs:annotation>
			</xs:element>
		</xs:sequence>
	</xs:complexType>
	<xs:complexType name="materialType">
		<xs:sequence>
			<xs:element name="value" type="ids:idsValue" minOccurs="0"/>
		</xs:sequence>
	</xs:complexType>
	<xs:complexType name="requirementsType">
		<xs:sequence maxOccurs="unbounded">
			<xs:element name="entity" minOccurs="0">
				<xs:annotation>
					<xs:documentation>Make sure 'Name' value of requirements entity is the same as the 'applicability' node, or a wildcard (inclusive pattern).</xs:documentation>
				</xs:annotation>
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:entityType">
							<!-- 
								Contrary to other requirements facet extensions, cardinality is not available in the entityType facet when used for requirements.
								Its cardinality state is always considered to be "required".
								Constraining the acceptable values is achieved by specifying criteria via with xs:Enumeration and xs:Pattern, rather than the negative form.
								This is possible because the list of options is finite and mandated by the IFC schema, so prohibited constraints are superfluous.
								This choice allows for improved user experience in the editors.
							-->
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
			<xs:element name="partOf" minOccurs="0" maxOccurs="unbounded">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:partOfType">
							<xs:attribute name="cardinality" type="ids:simpleCardinality" use="optional" default="required"/>
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
			<xs:element name="classification" minOccurs="0" maxOccurs="unbounded">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:classificationType">
							<xs:attribute name="uri" type="xs:anyURI" use="optional"/>
							<xs:attribute name="cardinality" type="ids:conditionalCardinality" use="optional" default="required"/>
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
			<xs:element name="attribute" minOccurs="0" maxOccurs="unbounded">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:attributeType">
							<xs:attribute name="cardinality" type="ids:conditionalCardinality" use="optional" default="required"/>
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
			<xs:element name="property" minOccurs="0" maxOccurs="unbounded">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:propertyType">
							<xs:attribute name="uri" type="xs:anyURI" use="optional"/>
							<xs:attribute name="cardinality" type="ids:conditionalCardinality" use="optional" default="required"/>
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
			<xs:element name="material" minOccurs="0" maxOccurs="unbounded">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:materialType">
							<xs:attribute name="uri" type="xs:anyURI" use="optional"/>
							<xs:attribute name="cardinality" type="ids:conditionalCardinality" use="optional" default="required"/>
							<xs:attribute name="instructions" type="xs:string" use="optional">
								<xs:annotation>
									<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
								</xs:annotation>
							</xs:attribute>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
		</xs:sequence>
	</xs:complexType>
	<xs:complexType name="specificationType">
		<xs:sequence>
			<xs:element name="applicability" type="ids:applicabilityType"/>
			<xs:element name="requirements" minOccurs="0">
				<xs:complexType>
					<xs:complexContent>
						<xs:extension base="ids:requirementsType">
							<xs:attribute name="description" type="xs:string" use="optional"/>
						</xs:extension>
					</xs:complexContent>
				</xs:complexType>
			</xs:element>
		</xs:sequence>
		<xs:attribute name="name" type="xs:string" use="required"/>
		<xs:attribute name="ifcVersion" use="required">
			<xs:simpleType>
				<xs:list>
					<xs:simpleType>
						<xs:restriction base="xs:string">
							<xs:minLength value="1"/>
							<xs:enumeration value="IFC2X3"/>
							<xs:enumeration value="IFC4"/>
							<xs:enumeration value="IFC4X3"/>
						</xs:restriction>
					</xs:simpleType>
				</xs:list>
			</xs:simpleType>
		</xs:attribute>
		<xs:attribute name="identifier" type="xs:string" use="optional">
			<xs:annotation>
				<xs:documentation>Author of the IDS can provide an identifier to the specification. This is intended to be a machine readable identifier. Beware: because of the possibility to combine different 'specification' elements from several ids files this cannot be enforced/assumed as (global) unique.</xs:documentation>
			</xs:annotation>
		</xs:attribute>
		<xs:attribute name="description" type="xs:string" use="optional"/>
		<xs:attribute name="instructions" type="xs:string" use="optional">
			<xs:annotation>
				<xs:documentation>Author of the IDS can leave instructions for the authors of the IFC. This text could/should be displayed in the BIM/IFC authoring tool.</xs:documentation>
			</xs:annotation>
		</xs:attribute>
	</xs:complexType>
	<xs:complexType name="specificationsType">
		<xs:sequence>
			<xs:element name="specification" type="ids:specificationType" minOccurs="1" maxOccurs="unbounded"/>
		</xs:sequence>
	</xs:complexType>
	<xs:simpleType name="relations">
		<xs:restriction base="xs:string">
			<xs:enumeration value="IFCRELAGGREGATES"/>  
			<xs:enumeration value="IFCRELASSIGNSTOGROUP"/> 
			<xs:enumeration value="IFCRELCONTAINEDINSPATIALSTRUCTURE"/> 
			<xs:enumeration value="IFCRELNESTS"/> 
			<xs:enumeration value="IFCRELVOIDSELEMENT IFCRELFILLSELEMENT"/> 
		</xs:restriction>
	</xs:simpleType>
	<xs:simpleType name="upperCaseName">
		<xs:restriction base="xs:normalizedString">
			<xs:pattern value="[A-Z]+"/>
		</xs:restriction>
	</xs:simpleType>
	<xs:simpleType name="simpleCardinality">
		<xs:restriction base="xs:string">
			<xs:enumeration value="required"/>
			<xs:enumeration value="prohibited"/>
		</xs:restriction>
	</xs:simpleType>
	<xs:simpleType name="conditionalCardinality">
		<xs:restriction base="xs:string">
			<xs:enumeration value="required"/>
			<xs:enumeration value="prohibited"/>
			<xs:enumeration value="optional"/>
		</xs:restriction>
	</xs:simpleType>
	
</xs:schema>