3.5 Scaling and Freezing

As we have seen, all dimensions in a TFM file are expressed in design size units. The idea is to make it simple for TeX to scale a font. Indeed, when a TeX user does \font\foo=cmr10 at 12pt or \font\foo=cmr10 scaled 1200, all TeX has to do is change the font’s design size. The drawback, on the other hand, is that in order to actually use the various font dimensions, they need to be multiplied by the design size in question every time.