Proportions. Which x-height to define? Which descender depth? Defining these proportions are essential, and very strongly connected to the purpose of the type. The proportions within a certain typeface are influencing the way your type will work & look. For example, it's impossible to create a space saving newspaper typeface with an extremely wide body width.

x高度应该定多高？下伸部应该多长？确定这些比例至关重要，并且与字体的用途紧密相关。字体的比例将影响其外观及应用。比如说，如果你想设计一种节约版面的字体，那就不能给它设置极大的字宽。

Extremely short descenders will give a strange look to a text typeface. Even worse, they might not be visible at all anymore. But extremely short descenders can also be a smart decision, while creating a display or headline type. For a text typeface the ascender height should be as big or, even better, bigger than then cap height to give a optical pleasurable result (see drawing).

如果下伸部很短，字体看上去会很怪。或者更糟，阅读者可能根本无法发现它。但很短的下伸部也可能是一个聪明的决定，当它用于特排字体或者标题字体的时候。 对一个正文字体来说，上伸部最好是和大写高度一样（或者更高一些更棒），以获得良好的视觉效果。如图。

英文原文