The basic building blocks of STEM – services, resources, and so on – have been carefully developed so that they can be identified with a wide variety of real-world entities, and so that the corresponding inputs and results can be interpreted with as much flexibility as possible.
In order to turn this flexibility to your advantage, STEM lets you annotate input data throughout the modelling process. Notes are stored with the model and drawn to the attention of anyone looking at the data. The subjective judgements made when defining inputs may not always be clear to someone else working on the same project, or even to yourself at a later date.