The required n attribute is the number of external product definitions in this list.
Source
<xs:element name="DefinitionExternal" type="DefinitionExternalType" minOccurs="0"><xs:annotation><xs:documentation>The optional DefinitionExternal element is a part definition in non-QIF format.</xs:documentation></xs:annotation></xs:element>
<xs:element name="PartFamily" type="PartFamilyType" minOccurs="0"><xs:annotation><xs:documentation>The optional PartFamily element gives information about the part that is useful for inspection planning.</xs:documentation></xs:annotation></xs:element>
The PartType is the part type. It contains a set of entities, defining a feature (body), which can be instantiated multiple times in the CAD scene. Use of parts simplifies maintenance of identical features and reduces the total amount of scene data.
The optional size attribute defines a recommended size for visualization of an infinite drawable element such as plane, cylinder, axis, etc., or objects without explicit geometric parameters (e.g. coordinate system).
The optional transparency attribute defines the transparency property of a model entity.
Source
<xs:complexType name="PartType"><xs:annotation><xs:documentation>The PartType is the part type. It contains a set of entities, defining a feature (body), which can be instantiated multiple times in the CAD scene. Use of parts simplifies maintenance of identical features and reduces the total amount of scene data.</xs:documentation></xs:annotation><xs:complexContent><xs:extension base="PartAssemblyBaseType"><xs:sequence><xs:element name="DefinitionExternal" type="DefinitionExternalType" minOccurs="0"><xs:annotation><xs:documentation>The optional DefinitionExternal element is a part definition in non-QIF format.</xs:documentation></xs:annotation></xs:element><xs:element name="PartFamily" type="PartFamilyType" minOccurs="0"><xs:annotation><xs:documentation>The optional PartFamily element gives information about the part that is useful for inspection planning.</xs:documentation></xs:annotation></xs:element><xs:element ref="FoldersPart" minOccurs="0"><xs:annotation><xs:documentation>FoldersPart is folders tree in the part.</xs:documentation></xs:annotation></xs:element></xs:sequence></xs:extension></xs:complexContent></xs:complexType>