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10.2 Encoding Tables
What is an encoding table and why is there more than one?
Encoding tables are tables computers use to map keystrokes to font glyphs. Your keystroke generates a
numeric code and the computer consults an encoding table for the Helvetica font. The encoding table tells the
computer which glyph is associated with that numeric code, in this case the glyph for the upper case ‘A’. The
computer displays the upper case ‘A’ glyph for the Helvetica font on the screen.
10.2.1 Why have different encoding tables?
The obvious immediate strategy was to extend the ASCII character set. Each character in the standard ASCII
character set fits in a single byte, but it uses only seven of the eight bits in the byte to represent characters.
Using the full 8 bits of a byte to represent a character increased the number of characters you could represent
from 128 to 255 and made it possible to represent many more languages.
Other strategies also developed for multi-byte character sets, such as those for the Chinese, Japanese and
Korean languages.
10.2.2 Encoding Tables in PlanetPress Design
Encoding tables can vary across platforms. When you create your documents in PlanetPress Design, you want
to ensure that the input data the document receives maps to the correct glyphs in the output. You use
encoding tables to make any necessary adjustments.
In PlanetPress Design you specify the encoding table you want a given style to use, or you define your own
encoding table for that style. You can rearrange the glyphs in the encoding table, altering the glyph associated
with a specific numeric code. You can also add glyphs to the encoding table from the list of all glyphs in the
font. Not all glyphs in a font necessarily appear in an encoding table.
You also specify an encoding table for the font you select to display the sample data file in the Data Pane.
There are four key points to keep in mind as you work with encoding tables in PlanetPress Design:
1. A font usually contains more glyphs than an encoding table references.
2. Different fonts have different glyphs. If you use two different fonts, there may be differences in the
glyphs available in each.
3. Different encoding tables reference different glyphs and/or may place the same glyphs in different
positions. If you use the same font but a different encoding table, the glyph that represents a given
input character may change.
4. You can edit the encoding table a style uses, and adjust both the glyphs the encoding table references
and the positions of those glyphs within the encoding table. You cannot edit the encoding table for the
font you use to display the sample data file.The output of the document always reflects what appears in
the data selections on the document page.
Related topics:
• Text and Box Objects (Page 119)
• Styles (Page 119)
• Double-byte Character Sets (Page 121)
• CID-Keyed Fonts (Page 122)
• Arabic Content in PlanetPress Design Documents (Page 123)
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