Tags are the core of the Connectivity Model. Most objects within an asset, either a plant or a ship, will be tag objects or objects that are specializations of a tag. All named items, other than breakdown items, like areas and units or documentation, are tag objects, or more likely, specializations of a tag. Therefore, equipment is a tag, as are nozzles and internal components.
A pipeline is a tag, as are the pipe runs that contribute to it and all the pipes, elbows, fitting, and so forth that belong to it.
An instrument loop is a tag and so are its instruments and wiring.
Although Tag is a class definition within the Common Schema, all tag objects are reclassified as objects of a class type that is a specialization of Tag once the object's type is known. Equipment will be classified as Equipment; pipe will be classified as Pipe; instrument will be classified as Instrument; pipeline will be classified as Pipeline; and so forth. Only objects with an unknown type will result as an instance of a Tag. As for the Common Schema, tag objects are typically accessed by their more specific entity type using the Common EDM.