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.
It is not the goal that should give you pleasure, but the path you have chosen. Write music and take lessons. A musican told me once that if I want to become a composer, all I have to do is write music. It's just a matter of experience, he said.