Centuries provide a chronological framework for compositions, events, and recordings, although a work’s date may differ greatly from the date of its sound recording. A nineteenth-century repertory can survive in a performance recorded a hundred years later, with altered instruments and arrangements. In Mexico, political, technological, and musical changes do not align neatly with century boundaries. This category supports historical browsing while encouraging users to distinguish the date of composition, period of practice, commercial release, and recording session whenever those details are documented.