喺2010年中繼資料通常係數碼形式；而喺1960同70年代嘅傳統卡片目錄，都係中繼資料嘅例，因為呢啲卡片包含有關圖書館（作者，標題，主題等）中嘅圖書資訊。
In 2010 relay materials were usually in digital form, while in the 1960s and 70s traditional card catalogs were also examples of relay materials because these cards contained information about the book in the library (author, title, subject, etc.).