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.
Some composers use instruments to help them as they write music. Others use software that allows them to hear a piece without musicians. Some music directors and composers give private music lessons to children and adults. Others work as music teachers in elementary, middle, or high schools.