phases of its service life. The document does not impose design or test specifications. Rather, it describes the environmental tailoring process that results in realistic materiel designs and test methods based on materiel system performance requirements. Finally, there are limitations inherent in laboratory testing that make it imperative to use proper engineering judgment to extrapolate laboratory results to results that may be obtained under actual service conditions. In many cases, real-world environmental stresses (singularly or in combination) cannot be duplicated in test laboratories. Therefore, users should not assume that an item that passes laboratory testing also will pass field/fleet verification tests. History and evolution of MIL-STD-810 In 1945, the Army Air Force (AAF) released the first specification providing a formal methodology for testing equipment under simulated environmental conditions. That document, entitled AAF Specification 41065, Equipment - General Specification for Environmental Test of, is the direct ancestor of MIL-STD-810. In 1965, the USAF released a technical report with data and information on the origination and development of natural and induced environmental tests intended for aerospace and ground equipment. By using that document, the design engineer obtained a clearer understanding of the interpretation, application, and relationship of environmental testing to military equipment and materiel. The Institute of Environmental Sciences and Technology (IEST), a non-profit technical society, released the publication History and Rationale of MIL-STD-810 to capture the thought process behind the evolution of MIL-STD-810. It also provides a development history of test methods, rationale for many procedural changes, tailoring guidance for many test procedures, and insight into the future direction of the standard. The MIL-STD-810 test series originally addressed generic laboratory environmental testing. The first edition of MIL-STD-810 in 1962 included only a single sentence allowing users to modify tests to reflect environmental conditions. Subsequent editions contained essentially the same phrase, but did not elaborate on the subject until MIL-STD-810D was issued marking one of the more significant revisions of the standard with its focus more on shock and vibration tests that closely mirrored real-world operating environments. MIL-STD-810F further defined test methods while continuing the concept of creating test chambers that simulate conditions likely to be encountered during a product's useful life rather than simply replicating the actual environments. More recently, MIL-STD-810G implements Test Method 527 calling for the use of multiple vibration exciters to perform multi-axis shaking that simultaneously excites all test article resonances and simulates real-world vibrations. This approach replaces