body: Metric compatible fonts (typically open-source) copy certain metrics from a (typically copyrighted) "source font". "Advance width" at least, and maybe other metrics (I have seen discussions of copying kerning data). Why is this not copyright infringement? Presumably the designer of a metric compatible font is not printing the source font and measuring it. They are using the *exact* metrics to achieve exactly the same horizontal spacing.
  
  
  Why does the creation of a metric compatible font not constitute copyright infringement? 
  
  
  
title: Why are Metric Compatible fonts not copyright infringement?