本文件解释了ISO 11171:2016中定义的两种可接受的粒度报告方法μm（c）和μm（b）的使用。它还解释了存在两种替代尺寸报告方法的原因及其对颗粒计数和过滤β比率数据的影响。

This document explains the use of the two acceptable methods of reporting particle size, μm(c) and μm(b), that are defined in ISO 11171:2016. It also explains the reasons for the existence of two alternative size reporting methods and its implications with respect to particle count and filter Beta Ratio data.