The control value table (‘cvt’) contains values defining lengths, widths, and angles of glyph features. Some values are specific to certain glyphs. Other values apply to the entire font or a group of glyphs, such as all uppercase characters. All control values have an identification (ID) number, as well as an attribute providing information about the type of glyph or feature to which it pertains (for details, see “Reading ‘Cvt’ Entries”).
Visual TrueType imports a template for the ‘cvt’ table when you prepare the font (see “Preparing the Open Font”). At any time, you can choose Control Values on theViews menu and modify the contents of that table three ways:
Fill in the control values indicated in the template, then add your own ‘cvt’ entries starting with the next available ID number.
Create the ‘cvt’ table from scratch by opening the Control Value window and replacing the template with entries you type (see “Editing Text”).
Import a ‘cvt’ table from another font to replace the contents of the Control Value window (see “Importing Text”).
All control values are in F-units scaled to the ppem height of the grid in use by the rasterizer.