View TRAK:Item
These are not maintained on this site. The https://trakmetamodel.sourceforge.io project site lists the metamodel elements, properties and property values together with diagrams and definitions.
The Item element details are at:-
Other Frameworks
The nearest equivalent in MODAF and NAF is Information Element although this can only represent an information item and not materiel or energy:
References
Category:Metamodel -> Stereotype