Location 1 — Improve vision
Location 2 — Correct vision
Location 3 — Position lenses
Location 4 — Select eyeglasses and Select contact lenses
The correct sequence is Improve vision → Correct vision → Position lenses and Secure lenses → Select eyeglasses and Select contact lenses . In a FAST diagram, the “How” direction moves from the broader purpose toward the more specific means of accomplishing that purpose. SAVE defines FAST as the Function Analysis System Technique, a diagrammatic representation of the HOW-WHY logic of functions and their interrelationships. It also defines the function logic path as the functions connected to each other in that HOW-WHY logic direction.
Improve vision is the higher-order purpose. Asking “How do we improve vision?” leads to Correct vision , which is the basic function of prescription eyeglasses. Asking “How do we correct vision?” leads to Position lenses and Secure lenses , because the corrective lenses must be properly located and held relative to the eyes. Asking “How do we accomplish that solution approach?” leads to Select eyeglasses and Select contact lenses , representing the lower-order choice of a corrective device or method.
The distractors are secondary/supporting functions. Secure position , Resist damage , and Complement appearance may support performance, durability, or user acceptance, but they are not the primary “How” logic path for correcting vision.
References/topics: Function Analysis Phase; FAST Diagram; HOW-WHY Logic; Function Logic Path; Higher-Order Function; Basic Function; Lower-Order Function.
