[DX] CMI: see if we can make those "storage" numbers in .json files less cryptic.

This could be related to #1345...

{
    "_config_name": "some.config",
    ...
    "storage": 4,

...means "default" ^^

{
    "_config_name": "some.config",
    ...
    "storage": 2,

...means "overwritten" ^^

Is there a 1 and a 3? ...what about a 0? ...does this have negative values? What is this in general?