The Ahem font was developed by Todd Fahrner to help test writers
develop predictable tests. The font's em square is exactly square.
Its ascent and descent is exactly the size of the em square. This
means that the font's extent is exactly the same as its line-height,
meaning that it can be exactly aligned with padding, borders, margins,
and so forth.

The font's alphabetic baseline is 0.2em above its bottom, and 0.8em
below its top. The font has an x-height of 0.8em.

The font has four main glyphs:

  'X' U+0058 A square exactly 1em in height and width.

  'p' U+0070 A rectangle exactly 0.2em high, 1em wide, and aligned so
             that its top is flush with the baseline.

  'É' U+00C9 A rectangle exactly 0.8em high, 1em wide, and aligned so
             that its bottom is flush with the baseline.

  ' ' U+0020 A transparent space exactly 1em high and wide.

Most other US-ASCII characters in the font have the same glyph as X.

Additionally, the following Unicode formatting characters are assigned
appropriate glyphs so that they may safely be used in tests as well:

  U+2002 - en-space
  U+2003 - em-space
  U+2004 - 3-per-em space
  U+2005 - 4-per-em space
  U+2006 - six-per-em space
  U+2009 - thin space
  U+200A - hair space
  U+200B - zero-width space
  U+200C - zero-width non-joiner
  U+200D - zero-width joiner
  U+3000 - ideographic space
  U+FEFF - zero-width non-breaking space

The Ahem font belongs to the public domain as described in COPYING.

Acknowledgements:
  v1 The font was originally created by Todd Fahrner in the late 90s.
  v2 It was updated by Paul Nelson in the mid 2000s to add x-height
     information to the OS/2 table and to add the space and non-breaking
     space glyphs.
  v3 It was further updated by Sergey Malkin to include the non-ASCII
     space glyphs.
