1. Typing notifications (which contain a single room_id)
2. Read receipts (which can contain multiple room_ids)
3. Presence updates (which do not contain room_ids)

Typing Notification EDU Example:

{
  "edu_type": "m.typing",
  "content": {
    "room_id": "!roomid:example.com",
    "user_id": "@user:example.com"
  }
}

Read Receipt EDU Example:

{
  "edu_type": "m.receipt",
  "content": {
    "!roomid1:example.com": {
      "$eventid:example.com": {
        "@user:example.com": {
          "ts": 1436451550453
        }
      }
    },
    "!roomid2:example.com": {
      "$eventid:example.com": {
        "@user:example.com": {
          "ts": 1436451550453
        }
      }
    }
  }
}

Presence Update EDU Example (without room_id):

{
  "edu_type": "m.presence",
  "content": {
    "user_id": "@user:example.com",
    "presence": "online",
    "last_active_ago": 2478593,
    "currently_active": true
  }
}