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.
If you're thinking of becoming a film composer, you probably love movies and are a talented musician who enjoys composing. And based on responses of 12 film composers to a Variety magazine question, you've probably felt that way for a long time.