What does a Write operation imply

From several discussions, we are starting to rely on side effects to update certain resources, especially containment triples.

This opens the question: What is really a write operation?

It is pretty clear that when you write to a resource, that's a write operation. It gets more unclear when there are updates done by the server as a side effect.

We could adopt the interpretation that if the state of a resource Q is altered by an operation on a different resource R, that operation requires write privileges on that resource Q, even if it R is the resource identified by the request-URI.

One implication of this idea is for example that deleting a resource R requires write privilege on the container C, since it requires updating the containment triples.

Start with the issue's seven comments and the discussions it references. Identify an agreed definition of a write operation, including server-side side effects and deletion of a resource from a container. Done means the authorization implications are resolved and documented in the specification.