First we must use the services of the Prayer Book, obeying its rubrics. Among the latter is the Ornaments Rubric, which refers us to the church arrangements and ceremonial adjuncts of the older tradition, as they were used either on the eve of the introduction of the First Prayer Book or immediately after it had been introduced. Then we must find out what that tradition was, and follow it, except where it is inconsistent with the later and living authority of the Prayer Book. For this tradition, the Sarum books are the principal, though not the only source. That is the English Use.
Francis C Eeles, "Prayer Book Revision and Christian Reunion"