本文件规定了第二代银明胶和重氮缩微品的视觉漫反射透射密度，以及第二代囊泡缩微品的投影密度。它还规定了测量方法。 不适用于技术图纸和其他图纸办公室文件的缩微副本。

This document specifies visual diffuse transmission densities for second generation silver-gelatin and diazo microforms and projection densities for second generation vesicular microforms. It also specifies methods of measurement. It does not apply to duplicates of microforms of technical drawings and other drawing office documents.