The closer the tool is in its relationship to the OS, the higher the level of pure machine technology. Likewise, the closer it lies to the AP the greater the emphasis on its understanding of the operator's needs.
各種軟體中，與硬體愈接近，如操作系統及有些資源軟體，開發所需的技術愈高；反之與使用者愈接近者，如應用軟體，技術層次較低，但要對使用者的需求充分瞭解，設計出來的軟體才能合用、好用。