A Point_property_definition is an Independent_property_definition that has as its criterion for membership a single magnitude or nature of a property.
A Point_property_definition has no tolerances.
NOTE - A Point_property_definition can be a member of a discrete Property_space such as 'number of bolt holes'. In this case, the absence of a tolerance is reasonable.
A Point_property_definition can be a member of a continuous Property_space such as 'mass'. In this case, the possession of the Point_property_definition by a product design is inevitably an approximation because there must be some tolerance or no individual could ever comply with the design.
EXPRESS specification:
*) ENTITY Point_property_definition SUBTYPE OF (Independent_property_definition); END_ENTITY; (*