Elasticsearch conditional filter

If I understood, is that?if type == a, all documents that have a will return.And if type == b and the field foo is not there they will return, make sense?

{   "query": {      "filtered": {         "query": {            "match_all": {}         },         "filter": {            "bool": {               "should": [                  {                     "term": {                        "type": "a"                     }                  },                  {                      "bool": {                          "must": [                             {                                 "term": {                                    "type": "b"                                 }                             }                          ],                          "must_not": [                             {                                 "missing": {                                    "field": "foo"                                 }                             }                          ]                      }                  }               ]            }         }      }   }}