The Adobe Type 1 Font Format book (PDF: 445 KB) - Adobe Partners

CHAPTER 3
Character Outline
Considerations
Character description is the heart of any Type 1 font program.
Each character shape comprises a path drawn by a series of Post-
Script language programming statements. Each character in a
Type 1 font can consist of no more than one such path. Of course,
this one path may contain several subpaths.
3.1 Character Geography
Although there are typographic terms for a wide variety of character
features, discussion here will be limited to those features
relevant to Type 1 font characters and the Type 1 hinting mechanism.
The main vertical strokes of a character are generally known as
vertical stems, and the horizontal strokes are known as horizontal
stems. Stems can be straight or curved; see Figure 3a that
follows. For example, in a Type 1 font character, the top and
bottom curved strokes of an “O” can be considered horizontal
stems, and the left and right sides can be considered vertical
stems.
In addition to obvious stem-like features of a character, it is also
important to identify serif shapes. For Type 1 hinting purposes,
the serifs on an “I” are considered horizontal stems. Similarly, the
vertical serifs on the cross stroke of a “T” are considered vertical
stems.
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