The NonShapeFeatureDefinitionBaseType is the abstract base type for non-shape feature definitions. A non-shape feature definition holds that portion of non-shape feature nominal information which can be shared among several features, e.g. feature size.
The id attribute is the QIF id of the feature, used for referencing.
Source
<xs:complexType name="NonShapeFeatureDefinitionBaseType" abstract="true"><xs:annotation><xs:documentation>The NonShapeFeatureDefinitionBaseType is the abstract base type for non-shape feature definitions. A non-shape feature definition holds that portion of non-shape feature nominal information which can be shared among several features, e.g. feature size.</xs:documentation></xs:annotation><xs:complexContent><xs:extension base="FeatureDefinitionBaseType"/></xs:complexContent></xs:complexType>