The text following the example of removing a comment from a photo states "to-many relationships have set-like behavior in JSON API"

I don't see this "set-like behavior" mentioned anywhere in the JSON Patch RFC, so it should be explicitly defined.

It seems there are four salient points:

1. Sets are represented as JSON Arrays
2. The order of that array should be explicitly ignored
3. add operations should use only the end-of-the-array reference ("-") as their target
4. References should be by ID rather than array index (see change link removal example to be "set-like" rather than "array-like" #99)

Does this sound good? If so, I can go ahead and submit a patch for this.