A domain is a set of objects, properties, relations and functions, together with a set of accepted statements about those objects, properties, relations and functions.
Here 'object' and 'item' cover objects, properties, events — anything of which one can be conscious.
This is useful for characterization of microstructures, appraisal of defects, and evaluation of objects properties.
The contents of mental representations are typically taken to be abstract objects (properties, relations, propositions, sets, etc).
And the entities invoked (objects, properties, and times) should be perfectly familiar to all but the most austere nominalist.
The answer to this question given by a proponent of Russellian propositions is: objects, properties, relations, and functions.
To avoid confusion, Dummett calls the first range of distinctions (among logical categories of objects, properties, relations, etc).
Thus a typed structure of properties is obtained: properties of ground objects, properties of ground objects and classes of ground objects, and so on.
This is the property of being about or directed at objects, including not only real concrete objects, but also abstract and fictional objects, properties, and states of affairs.
Secondly, although in introducing the notion of realism above mention is made of objects, properties, and facts, no theoretical weight is attached to the notion of a 'fact', or the notions of 'object' and 'property'property
