Properties are pertinent information for a Type or a Relation, used to define their content structure. Constraints on the content can be enforced through rules on properties.
For example, consider a Location Type which may have properties such as Name, Description, Address, Phone Number and GeoCode. Each property will have a an associated data type and may have one or more constraints. The Type may have a relation Check-In with the User Type. This relation may have properties Time, Comment and Photo.
In a UML paradigm, Properties can be considered to be like Attributes. In a RDBMS paradigm, Properties can be considered to be like Columns.
