anchor.diff:  
   [source,js]
   --------------------------------
  -{
  +GET /index/type/_rank_eval
  +{
  +    "requests": [
  +    {
  +        "id": "JFK query", 
  +        "request": { "query": { "match_all": {}}},
  +        "ratings": []  
  +    }],
       "metric": {
          "dcg": {
  -            "normalize": "false"  <1>
  +            "normalize": false                          <1>
          }
       }
   }
   --------------------------------
  +// CONSOLE
   
   <1> Set to true to compute nDCG instead of DCG, default is false.
   
  
positive.code:           "_id": "30900421",
            "_index": "enwiki_rank"
          }],  
        "summary_fields": ["title"],                      <8>
      },
      "metric": {                                         <9>
        "reciprocal_rank": {}
     }
  
negative.code:           "_type": "page",
            "_id": "30900421",
            "_index": "enwiki_rank"
          }],
        "params": {
          "query_string": "JFK",                          <2>
          "wiki_field": "opening_text"                    <2>
        }
      }],
      "metric": {
        "precision": {
  