Performers of music practised and perpetuated by oral tradition are guided by their knowledge of repertoire, by awareness of usages, procedures and techniques, and above all by their musicianship. Among the Gogo of Tanzania, as indeed among other societies with oral music tradition, these enable performers not only to reproduce what they have learnt, but also to re-create it where tradition allows it; they enable them to make their own additions to existing repertoire or bring new musical types into being. Thus a traditional composer of a particular piece of music need not provide everything for those who learn his music from him. Only the essentials such as the basic text, the melody, type of accompaniment need be provided or suggested.