編目員用詞匯O

Object　實物；參見Artefact, Realia
    Open entry　“開口”款目
    Optical disc (Electronic resources)　光盤（電子資源）；參見Disk (Electronic resources)
    Other title information　其他題名信息
    Overhead Projectual　投影圖像；見Transparency.
    Overlay　透明復(fù)蓋片、疊片