Equipments described by this specification are intended for use in testing equipments and systems in the worldwide natural and controlled environments in which military equipments are operated (on a continuous or intermittent basis for extended periods of time), either stored or transported or both, including utilization in all types of moving military and commercial vehicles (land, sea, and air). The extent of equipment's penetration (levels of use) into the military environment is limited by its classification (type, class, style, and color, as covered in 1.2).selection of the correct class is essential to ensure procurement of the desired equipment. This general specification can be used to procure quality commercial off-the-shelf (COTS) (see 6.3.2.9) test equipment (Type III), test equipment designed specifically for military use (Type I) , or commercial test equipment modified for specific military requirements (Type II). The environmental classes and other requirements of this specification represent the majority of clearly discernible levels of the military environment within which an item will be used. In the case where needs supersede requirements, this specification can be referenced in part. Where environmental needs overlap specific classes or styles, the lowest appropriate class or style (lowest environmental resistance) will form the basic requirement(s), and the additional specific requirements should be selected from the higher classes. May alter the environmental resistance of equipments designed to operate from either internal or external power sources or both. Preparers of detailed specifications are directed to 6.5.