Linking with ‘Cvt’ Values

A font should have certain constant relationships between glyphs. For example, the dominant weight of the stems should apply to round stems, as well as straight stems, and certain control points should fall on the baseline. You can achieve this control over relationships by having links refer to entries in the control value table (‘cvt’).

By default, Visual TrueType assumes that every link should refer to a ‘cvt’ value. That value specifies how far, in whole pixels rounded to the grid at the current ppem size, the child point is from the parent point.

Several links can refer to the same control value. This helps control consistency throughout the font at different point sizes and device resolutions.

Only unique distances unrelated to any other distance don’t require a ‘cvt’ value. A link without a ‘cvt’ value is called a distance.