User Guide

have Fontographer Auto Kern the rest, and be assured that
it won’t readjust any of the ones you created.
Check Don’t kern numerals with numerals if you don’t
want any kerning pairs created for the numerals. While
number pairs often could benefit from kerning pairs, that
will mess things up if the numbers ever have to appear in
vertical columns: the columns of numbers won’t line up
perfectly if some of the numbers are involved in kerning
pairs.
Check Don’t kern lowercase to uppercase if you want
Fontographer to skip all kerning pairs in which the first
character is lowercase and the second character is
uppercase. Having this checked is the recommended option,
since those sorts of letter combinations almost never occur.
The bottom parameter is among those that exert the most
influence on how many kerning pairs are created (unless
you limit Fontographer to a specific number of pairs, which
you can do in the “How many and how much” screen).
This value tells Fontographer when to make kerning pairs,
and when not to. When Fontographer is considering a
particular pair of letters and the kerning amount that
Fontographer has decided that pair needs is greater than or
equal the reference value (20 in this case), then those two
characters are made into a kerning pair. If the kerning
value Fontographer came up with for those two letters is
smaller than this value, then it is deemed a trivial kerning
pair, and Fontographer will not create a kerning pair for
those two letters.
You could sum up the preceding paragraph by saying that
the size of every kerning pair Fontographer makes will be
greater than or equal to the reference value you choose.
Therefore, the larger the number you enter, the fewer
kerning pairs will be created; the smaller the number, the
more kerning pairs will be created.
Once you have done all the kerning you think your font
needs, you can do Auto Kerning one last time, step up that
value to 100 or 150 em units, and be assured that the most
severely needed kern pairs will be created. For instance,
you might want to have kerning pairs involving just the
upper and lower case, but you also might want to have 10
or 20 pairs involving the accent characters or the symbol set
Fontographer User's Manual
5: Metrics: Spacing and Kerning Page #34