The purpose of this nomenclature guide is to promote more uniform and specific nomenclature throughout the airframe industry. Terms listed and defined are applicable to parts, aspects and characteristics of aircraft hydraulic and pneumatic fluid power systems and their components. Usage of nomenclature, where practicable, which conforms to definitions contained herein will serve to promote clarity and avoid misunderstanding. Some recommendations are made for restriction of terms which have become somewhat ambiguous or are considered less desirable than recommended nomenclature. Use of terms not defined herein is recommended only where those contained herein may not be applicable or adequate.