ISO 4148:2004规定了道路车辆专用警告灯的尺寸，以确保互换性和准确定位，同时考虑到投射光束垂直横截面中此类装置的光强度快速变化。它还规定了用于直接在车顶或车身钢板上安装特殊警告灯的磁性底座的测试方法。

ISO 4148:2004 specifies the dimensions of special warning lamps for road vehicles, in order to ensure interchangeability and accurate positioning, bearing in mind the rapid change of light intensity from such devices in a vertical cross-section of the projected beam. It also specifies methods for testing magnetic-base-mountings used to install special warning lamps directly on the steel sheet of the roof or body of a vehicle.