I just mean a mechanism for specifying metadata, and a little metadata. Off the top of my head, an optional header like "MergeMetadataObjectPropertyName: @merg

I just mean a mechanism for specifying metadata, and a little metadata. Off the top of my head, an optional header like "MergeMetadataObjectPropertyName: @mergeMetadata" Which would cause objects in the merge containing the property "@mergeMetadata" to be treated specially. The merge meta data could (optionally) specify an alternative to null for the special delete value. Or (optionally) specify the key value for an array representing an ordered, keyed collection. (Or, possibly, to specify the order value for an object used to represent a keyed, ordered collection.) I guess you could just do without the header and specify the metadata using magic values (in the same way null is used as a special value meaning delete), but it seems better to opt in to things things like that. (IMO, json merge patch would have been slightly better if it had no special values by default, but it's not bad. "null means delete" is a small thing, you probably need delete regardless, and, anyway, the ship has sailed on that one.)