Test equipment covered by this specification is intended for use in testing equipment and systems in the worldwide natural and controlled environments in which military equipment is 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 an equipment's penetration (levels of use) into the military environment is limited by its classification. Selection of the correct class is essential to ensure procurement of the desired equipment. Where needs supersede requirements, this specification can be referenced in part. Where environmental needs overlap specific classes, the highest appropriate class (lowest environmental resistance) will form the basic requirements, and the additional specific requirements will be selected from the lower classes. The inclusion of batteries may alter the environmental resistance of equipment designed to operate from either internal or external power sources or both. Any existing general purpose electronic/electrical test equipment assets or stock that have been procured to MIL-PRF-28800F, dated 24 June 1996, or to earlier versions are acceptable for use until depleted.