關於「Opal card」標籤，搜尋引擎有相關的訊息討論：

Opal Travel – Apps on Google Play評分 3.1 (4,713) · 免費 · AndroidOpal Travel is the official app for managing your travel across the public transport network in Sydney (Australia), and surrounding regions.缺少字詞： tw | 必須包含以下字詞：twThe Opal Card User (@TheOpalUser) / TwitterTweet