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Microsoft Typography | Developer information | VOLT | VOLT release notes
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Main project window

Main project Window

Main project Window [reproduced at 50%]

The Main project window provides a birds-eye-view of the OpenType Layout table structure of the font you are working on. OTL table generation is a well-defined, structured activity that makes use of a 'building block' concept. The individual panes contain details at different levels. The rightmost pane shows units called 'glyph groups'. The smallest unit of information being used from the font in generating glyph groups - is the glyph. These units help string together glyphs. Glyph groups are the building blocks for lookup generation. The lookup pane lists lookups used by features. These lookups string together glyph groups / glyphs; to enable glyph substitutions and positioning. The leftmost pane encompasses information from the lookup and glyph group panes; and also adds information about scripts, languages and features. It allows the font developer to see the overall structure of the OTL tables constructed for the font.

Viewing glyphs

By clicking on the 'Edit Glyphs' button you bring up the glyph grid where you can view glyphs, their names, CMAP entries and types assigned to them. For ligatures you can also set the number of components they have (which affects mark-to-ligature positioning lookups and caret placement inside ligatures).

The VOLT Glyph Editor

The VOLT Glyph Editor

Creating the feature tree

From the main project window you can create the Script / Language System / Feature / Lookup tree. Input each item in the form 'name <tag>' (with the tag in angular brackets). You can input the tag only or name only and VOLT will deduce the other part for all registered tags.

The VOLT Script / Language System / Feature / Lookup tree

The VOLT Script / Language System / Feature / Lookup tree

Script, language and feature tags

The list of registered tags is stored in file TAGS.txt (file updated 6 August 2002) in the application directory. Updates to this file will be available as we register more tags. In future versions of VOLT, the mechanism will be changed to getting the localized names through NLS+. The tags included in tags.txt are listed in the following tables. The order in which features appear in its table is for ease of locating features applied and does not imply nor affect the order in which lookups are processed.

Scripts, language systems and features are always sorted alphabetically. The order of these does not affect the processing order in the font.

The language systems with tag <dflt> are marked by VOLT as default language systems. Features with tag <dflt> are marked by VOLT as required features. Please note a difference with raw OTL format here where any feature or language system can be designated as required or default.

Adding lookups

To add lookups to features you have to create them separately in the 'lookup list' and then drag-and-drop them into corresponding features.

Lookups are not arranged alphabetically like the feature list. The order in which the lookups appear is the order in which they are executed, each one of them being called only once. Hence it is important that the order be worked out and thoroughly planned by the font developer.

To change the order of lookups, drag-and-drop them in the lookup list. This will change the order they appear in the feature tree as well.

Adding glyph groups

You can add glyph groups in the main project window. Having glyph groups does not have any effect on font functionality, but using predefined groups in lookups may really speed things up. To reference a groups in a substitution or positioning lookup, you have to write the group's name in angular brackets, e.g. <Capitals>.

A glyph group list and two glyph groups

A glyph group list and two glyph groups

Groups are always displayed in alphabetical order.


Anything that has a tag (scripts, language systems and features) may have a name with any kind of characters in it. These items are referenced by their tags. All names are case sensitive. Glyph names can contain only letters and digits. With VOLT version 1.1 we allow the use of '.' and '_' characters in glyph names.

this page was last updated 6 August 2002
© 2002 Microsoft Corporation. All rights reserved. Terms of use.
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Start | Project window | Glyph grid | Glyph group | GSUB | GPOS | Proofing | File | Samples
Microsoft Typography | Developer information | VOLT | VOLT release notes