This is a draft view presented early on in the Meld conversations (~ May 2020).  While this is focused on the "2-stream" (RA-2, RI-2, RC-2), it is also applicable to the "1-stream" (RA-1, RI-1, RC-1).

  1. RM defines the scope, and a few high level requirements.
  2. RA-2 defines the specific architecture and platform requirements, focused on containers.  Should have a list of relevant RM requirements.
  3. RI-2 is an implementation produced by LFN, intended to provide an example working implementation that passes RC-2 testing.  It has requirements for companies that wish to use this specific implementation.  A company may choose a different set of installation tools, provided the resulting implementation passes the RC-2.  Stack components might be different, although selection is highly dependent on what's required by name in RA-2.
  4. RC-2 is a test conformance suite that proves the company's implementation matches the RA-2 requirements.  RC-2 will have requirements for how a company sets up and operates the conformance tools.

Here is an analogy using everyday life concepts.

work streamConstruction analogy ("Like a ...")What it does
RAbuilding code in our local community.  Defined and maintained by a committee in the community government.Defines the requirements and specs of a finished wall in new construction - the intention is to ensure that walls are build strong and safe.  For instance, the building code might define the type of lumber and size, nail size and strength, distance between vertical studs, number of nails per linear foot, etc.
RI

home improvement store that the local community government selected to showcase a wall that matches to the local building code.

The local government may also have its own reference wall at the government office.

Home improvement store has a reference wall on display (eg, in US - Lowes, Home Depot, Menards).  The end-consumers who own the new construction can come to the store and see how it's built. 

  • The end-consumer can buy the supplies or maybe even a pre-fabricated wall at this store..
  • The end-consumer can go elsewhere to purchase supplies (maybe due to store or brand preference — which is ok, as long as those products conforms to the building code).
  • The end-consumer can buy a preformed wall from a company (then it's the company's job to ensure that the wall conforms to local building code, even though the homeowner is ultimately responsible).

The home improvement's requirements are defined to explain to the end-consumer how the reference wall was built in this store.  The store defines what brand of lumber used, how they constructed the wall, what type of tools they used.

The local community generally doesn't allow the local home improvement store to define or override the local building code (the requirements and specs of the finished wall).

RChome inspector who needs to make sure construction matches to the building code.

The inspector tests the wall to ensure conformance to the local building code.  Tools such as a level or tape measure are used to test for wall conformance.

The requirements to do an inspector's job are aligned to the test procedures and tools (they will obviously need to know the local building code).

The local community generally doesn't allow the inspector to define or override the local building code (the requirements and specs of the finished wall).