User Guide

those of the base character.
Now you can optionally set up some difference (in value) to
be applied to the base character’s attributes. For instance,
you could create an equivalence class that means certain
characters’ widths will be equal to a base character’s
width, plus 10 percent.
Next, you specify whether the class should be linked. If the
Link to base checkbox is checked, whenever the values in
the base character change, the corresponding values in all
the other characters in that class will be automatically
updated.
Finally, you can link everything together. This is similar to
the Link to base checkbox, but Link all means that if any of
the character’s controlled attributes change, all other
character’s attributes will be automatically updated
(including the base character).
Using these definitions, let’s explore the sample equivalence
class:
Our base character is “A”. That means that the attributes of
the “A” will determine what the other character’s attributes
are. We chose to control both the left sidebearing and the
width.
The other members of the equivalence class are “, , , ,
and .” This is a fairly typical class. All the members of it are
related rather obviously to the base character. Other
common classes are ones that link “E” with “, , ,” and so on.
There is nothing added to the base value. “A” is linked to all
the letters “, , , , and ”, but not vice versa.
When this class is applied, by accepting the dialog box, the
left sidebearings and widths of “, , , , and ” will all be made
equal to the left sidebearing and width of the base
character “A.” In addition, if you should ever edit the “A,”
either by changing its width or moving the outline around so
that the left sidebearing changes, all those other characters
will update automatically!
You can get pretty imaginative in figuring out which
characters should be linked to which others. For instance,
Fontographer User's Manual
5: Metrics: Spacing and Kerning Page #23