User Guide

FontLab 4
540
D e l t a In s t r u c t i o n s
Now you know all about the visual hinting commands that can be applied
to an outline at all PPMs. In addition to these commands the TrueType
hinting language lets you set special commands that will work only at
specific PPM sizes. These commands are called delta instructions.
There are two delta instructions for each hinting direction: middle delta
instructions and final delta instructions.
Final delta instructions are necessary when you want to slightly change the
instruction set - usually to add or remove some pixels: