LINE公式アカの「リッチメッセージ」の仕組み？

gistfile1.txt

    struct {
      1: field = "u4b49463b1f3a980ec6fa796249ad0206"
      4: field = "1170947380609"
      5: field = i64 1399082996227
      6: field = i64 0
      10: field = "「LINE レンジャー」1,000万ダウンロード＆TVCMスタート記念★2大プレゼント実施中！（このメッセージはスマートフォンでご確認ください）

全40種類！無料特製スタンプのGETはこちら
http://bit.ly/1n4uP3Y
ログインして限定レンジャー｢レアレッドブラウン｣をGET！
http://bit.ly/1q8IHtx
"
      14: field = false
      15: field = i32 0
      18: field = {
        "BOT_richId" = "8726"
        "MARKUP_JSON" = "{"canvas":{"width":1040,"height":1040,"initialScene":"initialScene"},"images":{"img":{"x":0,"y":0,"w":1040,"h":1040}},"scenes":{"initialScene":{"draws":[{"image":"img","type":"image","src":"img","x":0,"y":0,"w":1040,"h":1040}],"listeners":[{"type":"touch","action":"A","params":[0.0,0.0,520.0,1040.0]},{"type":"touch","action":"B","params":[520.0,0.0,520.0,1040.0]}]}},"actions":{"A":{"type":"web","text":"\u516840\u7A2E\u985E\uFF01\u7121\u6599\u7279\u88FD\u30B9\u30BF\u30F3\u30D7\u306EGET\u306F\u3053\u3061\u3089","params":{"linkUri":"http://bit.ly/1n4uP3Y"}},"B":{"type":"web","text":"\u30ED\u30B0\u30A4\u30F3\u3057\u3066\u9650\u5B9A\u30EC\u30F3\u30B8\u30E3\u30FC\uFF62\u30EC\u30A2\u30EC\u30C3\u30C9\u30D6\u30E9\u30A6\u30F3\uFF63\u3092GET\uFF01","params":{"linkUri":"http://bit.ly/1q8IHtx"}}}}"
        "SPEC_REV" = "1"
        "ORGCONTP" = "RICH"
        "seq" = "46"
        "ALT_TEXT" = "「LINE レンジャー」1,000万ダウンロード＆TVCMスタート記念★2大プレゼント実施中！（このメッセージはスマートフォンでご確認ください）

全40種類！無料特製スタンプのGETはこちら
http://bit.ly/1n4uP3Y
ログインして限定レンジャー｢レアレッドブラウン｣をGET！
http://bit.ly/1q8IHtx
"
        "PUBLIC" = "true"
        "DOWNLOAD_URL" = "http://dl-obs.official.line.naver.jp/r/talk/r/u4b49463b1f3a980ec6fa796249ad0206-1399082868626"
      ]
    }