Doctor : Prescription :: Architect : ? Choose the term that completes the analogy.

The relation is a professional : the paper he draws up telling others exactly what to carry out. A doctor writes a prescription for the chemist to make up; an architect draws a blueprint for the builder to work from. 'Building' is the thing finally raised, and it is raised by the contractor, not by the architect. 'Scale' is one of the instruments on his desk, and 'Site' is merely the ground the work stands on.