The following types of References provided with this document and OPC 10000-23 are used for modelling FunctionalEntities:

• HasSubFunctionalEntity indicates that a FunctionalEntity has a nested FunctionalEntity.
• IsHostedBy indicates that a FunctionalEntity needs the referenced Asset to provide its functionality.
• IsExecutingOn relates a FunctionalEntity to the execution environment it is currently executing on (e.g., hardware component, task or thread).
• RepresentsSameEntityAs (symmetric) relates two entities which represent the same entity in the real world. This Reference may be used, for example, to relate a FunctionalEntity with its counterpart in the event of redundant logic. Another example might be a sensor that is dual-ported and wired to two different input signals. These two FunctionalEntities could be related with RepresentsSameEntityAs.
• RepresentsSameFunctionalityAs (symmetric) relates two entities representing the same functionality. This Reference may be used, for example, to relate a FunctionalEntity with its counterpart in a companion specification.