anchor.diff:                      }
                   ],
                   "condition": {
  -                    "attributes": [ "temperature " ],
  +                    "attrs": [ "temperature " ],
                       "expression": {
                          "q": "temperature>40"
                       }
                    }
               },
               "notification": {
  -                "callback": "http://localhost:1234",
  -                "attributes": ["temperature", "humidity"],
  -                "throttling": 5,
  -                "count": 12,
  +                "http": {
  +                  "url": "http://localhost:1234"
  +                },
  +                "attrs": ["temperature", "humidity"],
  +                "timesSent": 12,
                   "lastNotification": "2015-10-05T16:00:00.00Z"
               },
               "expires": "2016-04-05T14:00:00.00Z",
  -            "status": "active"
  +            "status": "active",
  +            "throttling": 5,
           }
   
   
  
positive.code:     + `id` or `idPattern`: Id or pattern of the affected entities. Both cannot be used at the same time, but at least one of them must be set.
      + `type`: Type of the affected entities (optional).
  + `condition`: Condition that will trigger the notification. It can have two optional properties:
      + `attributes`: array of attribute names
      + `expression`: an expression composed of `q`, `georel`, `geometry` and `coords` (see "List entities" operation above
     about this field).
  
  A `notification` object contains the following subfields:
  
  + `attributes`: List of attributes to be included in the notification message. If not specified (or empty), all attributes are included
    in the notification. It also defines the order in which attributes will appear in notifications when `attrsFormat` `value` is used
    (see "Notification messages" section).
  + `callback` : URL pointing to the service which will be invoked when a notification is generated. A NGSIv2
    compliant server must support `http` URL schema, other schemas (e.g. schemas for web sockets) could also be supported.
  + `headers` (optional): a key-map of HTTP headers that will be included in the notification messages. Note that this cannot be used
    to override headers that make the notification inconsistent (e.g. `Content-Type: application/json`).
  + `query` (optional): a key-map of URL query parameters that will be included in the notification message.
  + `attrsFormat` (optional): specifies how the entities will be represented in notifications. Accepted values are
    `normalized` (the one used if the field is omitted), `keyValues` or `values`. If `attrsFormat` takes any value different
    than those an error will be raised. See detail in "Notification messages" section.
  + `throttling`: Minimal period of time in seconds which must elapse between two consecutive notifications. It
    is optional.
  + `timesSent` (not editable, only in GET operations): Number of notifications sent due to this subscription.
  + `lastNotification`: Last notification date in ISO8601 format.
  
  Notification rules are as follow:
  
  * If `attributes` and `expression` are used, a notification is sent whenever one of the attributes in the `attributes` list changes and
    at the same time `expression` matches.
  * If `attributes` is used and `expression` is not used, a notification is sent whenever one of the attributes in the `attributes` list changes-
  * If `attributes` is not used and `expression` is used, a notification is sent whenever any of the attributes of the entity changes and
    at the same time `expression` matches.
  * If neither `attributes` or `expression` are used, a notification is sent whenever any of the attributes of the entity changes.
  
  ## Subscription List [/v2/subscriptions]
  
  
negative.code: ### Notification templates
  
  Based on the "template" field defined as part of the subscription and in a macro replacement language
  that could be used in "payload", "url", "headers", "method" and "qs". Details TBD.
  
  ## Group API Entry Point
  
  