Version 1.1 of the specification is clear about the treatment of @-members contained in the JSON:API-defined objects of a document, but it's unclear how they should be handled in objects nested under attributes (which are not JSON:API-defined, but are defined entirely by the types of the application.

For example, in this document:

{"data": {
   "type": "person",
   "id": "42",
   "attributes": {
     "@at-thing": "ignore this",
     "address": {
       "@comment": "Would be nice to live here!",
       "street": ["123 Main St.", "Suite 24"],
       "city": "Someplace Warm",
       "state": "CA",
       "postcode": "90120"
   },
   "links": {
     "self": "/api/people/42"
   }
 },
 "links": {
   "self": "/api/people/42?include[person]=address"
 }
}

the @at-thing member should clearly be ignored, but should @comment be dropped as non-JSON:API data, or should it be passed along to the application as part of the address field?