Is the prototype not an output of the initial design process and an input into the validation process? IMO this is where Quality Management Systems tend to let us all down. We become consumed by the semantics and don't focus on the real issue of what value is added, regardless of what it is called.
I like the security and sense of "order" as much as anyone, but how much time do we spend trying to structure and pigeon hole certain aspects of what we do.
That said, please don't think I don't see this as a valuable question, we all need clarification, my opinion is that if your system effectively translates the requirements of whatever customer you have (internal or external), via your design process, your designs are validated against these requirements and the process is deemed effective and efficient to your organisation, then you can call the prototype whatever you like!
I like the security and sense of "order" as much as anyone, but how much time do we spend trying to structure and pigeon hole certain aspects of what we do.
That said, please don't think I don't see this as a valuable question, we all need clarification, my opinion is that if your system effectively translates the requirements of whatever customer you have (internal or external), via your design process, your designs are validated against these requirements and the process is deemed effective and efficient to your organisation, then you can call the prototype whatever you like!