This topic is about instrumentation and controls, and in particular how these are being represented in the RDL.
All Instrumentation & Controls classes are, in the top of their class hierarchies, strictly separated by function. In the table below this is shown for the first level in the hierarchy:
Click here for a report showing all 853 subclasses of INSTRUMENTATION FUNCTION.
No combinatory explosion
Since most instrumentation items and all controls are combinations of above functions the number of possible combinations is unmanageable. And they are not required either, because these combinations can be made on-the-fly in a kind of "cafetaria mode", similar to composing your food by selecting food from a counter.
An integrated measuring element of a transmitter, process switch, process gauge, or process-connected recorder gets a subtag (see B14-FT-101-E below) and is related to that instrument with an AssemblyOfAnIndividual template.
Combinations of functions are done by typing with the applicable functions (see B14-FRC-101 below, typed with RECORDER and CONTROLLER).
Using templates allows for a different choice of for a further specialization at a later time. Just deprecate the old template and create a new one, whilst maintaining the old template for an audit trail.
Below three examples are given: