Concept: Constraints

Constraints add additional limitation of possible data values or transformations or data processing.

Typical example is Boolean block type, where single attribute is used to store either false (0) or true (1) and additional values are ignored. Yet it is not defined how should system behave when any invalid value is actually used.

Constraints should make it possible to introduce additional rules and checking this rules should then assure, that values are not stored improperly.