Knowing the Score
The black and white of a score means simply knowing everything that is printed in the score from the first measure to the end. If the dynamics, phrasing, tempi, or basic shape is wrong, then the conductor does not know the score. But the gray area includes the intangibles: knowledge of stylistic concerns and traditions associated with a given piece. They are just as important to the knowledge of the score as the black-and-white notes found on the page. Coaches, even if they play almost exclusively from piano-vocal scores, need to be able to study the orchestral scores, improving those vocal scores with notations from the knowledge learned in the fuller score. This may also mean learning which editions of scores to trust and which ones to avoid.