Datum

Performing observations in the real world requires an ability to interact with the world, and perform data capture. This may be via measurement, either manual or with instruments, or by other means, such as classification, questionnaire, interviewing and so on. In engineering areas, measurement by devices is the main means of obtaining data; each measurement may obtain only a single or a few data items. For example a transducer that knows the tap position of a transformer, another transducer that obtains the output voltage and so on.

CRO treats data entities as fragments of information content extracted from reality via such means. It accordingly assumes that the results of data capture have to be integrated to create meaningfully complete information entities, even of sub-parts of any independent entity (such as an aircraft) whose description is being constructed.