User Guide

FontLab 4
196
StdHW, StdVW, StemSnapH and StemSnapV Parameters
From the Type 1 font specification you may know that in Type 1 fonts two types of standard stem
widths are used: Standard Width and Stem Snap Width. There is one standard width for each
direction and up to 10 stem snap values. In FontLab these values are united in the stem list. StdHW
and StdVW are taken from the first records in the stem lists. StemSnapH and StemSnapV records are
the remaining records in the stems' list.
FontLab also has a faster way to append stems to the list of standard stem
widths. Any vertical or horizontal hint may be used as a source of stem
width information. Just point the Edit tool at the hint, press the right
mouse button and select the Define a Stem command in the popup menu.
If this command is not accessible, it means that this stem is already in the
list.
To automatically calculate standard stem widths press the Auto
stems button.
How FontLab Calculates Standard Stems
FontLab can calculate standard stem widths only if some characters in the font have Type 1 hints.
1. It builds a table of all hints that are used in the font, sorts this table by frequency of usage and
selects the most frequently used hints.
2. All selected hints are then compared with these most frequently occurring stem widths and
hints with widths that are close together are combined into a single record.
3. The list is then sorted again.
4. The most frequently used elements are then selected and used as standard stems.