[Developers] Can't query for values of /type/key in a write?

[Shawn Simister]

I got the following unexpected error in a write query. Its seems that 
Freebase doesn't like it when I add a prefix to a key value but the 
documentation for the MQL write grammar doesn't say anything about that 
restriction. I'd like to be able to use the prefixes as named parameters 
in my code so hopefully this syntax is possible.

{
  "status": "200 OK",
  "create_nndb_person_key": {
    "code": "/api/status/error",
    "messages": [
      {
        "info": {
          "value": null,
          "expected_type": "/type/key",
          "mode": "write",
          "key": "value"
        },
        "query": {
          "person:id": "/guid/9202a8c04000641f800000000569f867",
          "type": {
            "id": "/user/narphorium/people/nndb_person",
            "connect": "insert"
          },
          "key": [
            {
              "error_inside": ".",
              "namespace": "/guid/9202a8c04000641f8000000008e5719d",
              "connect": "insert",
              "nndb_key:value": "243$002F000099943"
            }
          ]
        },
        "message": "Can't query for values of /type/key in a write, only 
those of /type/id",
        "code": "/api/status/error/mql/parse",
        "path": "key"
      }
    ]
  },
  "code": "/api/status/ok"
}

Thanks,

Shawn