These are the characters which are very often confused. For instance, in some typefaces I looks very similar to l or to 1. The same is for B and 8, 0, and O.
This dialog allows you to see how "different" these glyphs are.
See this post by Jeff Atwood for a comprehensive comparison of various fixed-width fonts. This is basically the same, but it's from pre-Vista era.
Anton Gogolev
2009-10-20 10:48:37