As mentioned in Types of Streams, streams can be considered as input, output or intermediate (based on their source and destination procedures) and bulk or discrete (based on the type of material they carry). The above classification of streams is based on the inherent nature and cannot be explicitly set by the user. We also already described that there’s one more classification based on economics or intended purpose for use of a stream and from that perspective streams can be designated as Raw Material, Revenue (or Credit), Cleaning Agent, or Waste (Solid, Aqueous Liquid, or Emission).
The stream’s identity is a property of only input or output streams (not intermediate) that supersedes its intended use and in a way, dictates how it should be considered from the economic perspective. Not only that, but it can also dictate the composition of the stream (if it’s an input stream) in a way that is locked and no longer available for editing. The options for what can be set as the identity of a stream depend on whether the stream is a process input or output.