What about this case?

| `{"event_type": "login"}`                 | `02 00` (object with 0 fields) | non-null      | null                           | `login`

Is it legal for an object that shredded perfectly to still have an empty object in the value column? It's sub-optimal but is it incorrect?

Conversely, what about this case?

| `{"event_type": "login"}`                 | null | non-null      | null                           | `login`

Is it allowed for an object that shredded perfectly to have NULL in the value column? Or is it required to have an empty object there? (guessing it's allowed to have NULL, and maybe even required to do so)

These are good points! I could add them but first need to have confirmation on expected behaviour from other collaborators.
For the first point, can we say that that the following is correct:

| Event object                            | `value`                        | `typed_value` | `typed_value.event_type.value` | `typed_value.event_type.typed_value` | `typed_value.event_ts.value` | `typed_value.event_ts.typed_value` | Notes                                                                                     |
|-----------------------------------------|--------------------------------|---------------|--------------------------------|--------------------------------------|------------------------------|------------------------------------|-------------------------------------------------------------------------------------------|
| INVALID CASE: `{"event_type": "login"}` | `02 00` (object with 0 fields) | non-null      | null                           | `login`                              | null                         | null                               | INVALID CASE: an empty object (object with 0 fields) is present for fully shredded object |

cc: @alamb @emkornfield

For the second point, i think it is described in the case one (fully shredded object), where value is null.

For the first point, can we say that that the following is correct:
[value of a perfectly shredded object is a variant object with no fields instead of NULL]

That's exactly my question... it's sub-optimal, but well-defined, and and I'm not immediately seeing why it would confuse or break readers?

True! Lets here from the other collaborators maybe? I can add this case to the table once we agree on it.
cc: @alamb @emkornfield

The table is already super wide; I'm not sure CASE adds enough information to be worth the space it consumes?

I added it for more clarity, but agree, it should be understandable just with INVALID as well

Not understanding the "while being null" part? What about just:

INVALID CASE: typed_value is present and value is not an object

Rephrased as per suggestion!