P156 occupies in Version 6.1

This property describes the maximal real volume in space that an instance of E18 Physical Thing has occupied during its lifetime with respect to a reference space relative to which the thing is at rest. In other words, it is the volume that contains all the points which the thing has covered at some time during its existence. In the case of an E26 Physical Feature the default reference space is the one in which the object that bears the feature or at least the surrounding matter of the feature is at rest. In this case there is a 1:1 relation of E26 Feature and E53 Place. For simplicity of implementation multiple inheritance (E26 Feature IsA E53 Place) may be a practical approach.

 

For instances of E19 Physical Objects the default reference space is the one which is at rest to the object itself, i.e. which moves together with the object. We include in the occupied space the space filled by the matter of the physical thing and all its inner spaces. 

 

This property is a shortcut of the fully developed path from ‘E18 Physical Thing’ through ‘P157 occupied’, ‘E92 Spacetime Volume’, ‘P159 has spatial projection’ to ‘E53 Place’. For some instances of E18 Physical Object the relative stability of form may not be sufficient to define a useful local reference space, for instance for an amoeba. In such cases the fully developed path to an external reference space and using a temporal validity component may be adequate to determine the place they have occupied.

 

In contrast to P156  occupies, the property P53 has former or current location identifies an instance of E53 Place at which a thing is or has been for some unspecified time span.  Further it does not constrain this reference space of the referred instance of P53 Place.