The number of units of useful information contained within a linear dimension.
信息密度在一个线性维度内有用的信息单元的个数
A unit of type width based on the number of times a character can be set in one linear inch.
印字宽度的单位，以一英寸直线距离上能安置的字符数计。
The number of units of useful information contained within a linear dimension, usually expressed in units per inch.
在一单位长度内包含的有用信息单位数。通常用每英寸多少单位表示。
