This SAE Recommended Practice provides test procedures, requirements, and guidelines for the system of optical warning devices used on emergency vehicles. The document was revised to unify the terminology and test methods with other Emergency Warning Lights & Devices documents. Also, changes were made to remove the duplication of test requirements between this document and SAE J595 and SAE J845 such that EWD Lamp Assemblies tested under those standards may be more easily evaluated per this document. 2.1.1 - SAE Publications section revised to remove publications not referenced within document. Removed SAE J575 and SAE J1889. 3.4, 3.5, 3.6, 3.7, 3.8 - Terminology is revised to match adopted terms of SAE J845: Lower Level Optical Warning Devices, Optical Power, EWD Lamp Assembly, Optical Warning Device, and Upper Level Optical Warning Devices. 3.9 - Updated Figure 1 to remove split zones previously used for intermediate vehicle size. 4.1.3 - Removed along with Section 7. 5.1 - Reworded to standardize testing to SAE J845 methods. 5.2 - Photometric Tests section now refers to SAE J845 in order to standardize test setup, procedure, and process. 6.3.2, 6.3.2.3, 6.4 - For consistency with industry definitions and practices: Length specified for midship device requirement revised to 7.6 m (25 feet), (previously 6.7 m (22 feet)). 6.4.1.4/6.4.2.2 Steady burning statement moved from 6.2.1 in order to be more closely tied to the applicable test. 6.4.2 (Previous) - Intermediate Emergency Vehicle section removed. Industry practice is to utilize the large vehicle requirements for vehicles in the category. The adjustment in length and height in other sections allows many vehicles previously defined as Intermediate to be categorized as Small. 6.4.2 - Small vehicle height revised to 96 inches, was 82 inches. 6.4.2.2 "Level" column removed from Tables 3A and 3B, no longer applicable. 7 - Guidelines section removed as this is not industry practice and is unwieldy and difficult in actuality. "Optical Warning Device" is substituted for "Warning Device" throughout document. References to "Intermediate Emergency Vehicles" removed throughout document. Sections 5.2, 6.4, and 7 as well as Tables 3A and 3B renumbered due to edits above.