Chart datum, level of water depth on a nautical chart. Datum or datum point, a (possibly arbitrary) reference baseline or point from which scientific measurements are made (from a Latin meaning of datum as a given, i.e. an accepted fact)
Music directors and composers must guide musicians and singers by preparing musical arrangements and helping them achieve the best possible sound. Musical talent. To become a music director or composer, one must have musical talent.
Music directors and composers often work as musicians or singers in a group, a choir, or an orchestra before they take on a leadership role. They use this time to master their instrument and gain an understanding of how the group functions.