Conditional Feature Code

Feature code can be wrapped in #ifdef blocks to limit it to variable fonts. Such a code block ends with a #endif line:

#ifdef VARIABLE
sub a by a.var;
#endif

Rules inside a #ifdef (if defined) block are included only in variable fonts. Use #ifndef (if not defined) to include feature rules only in non-variable fonts:

#ifndef VARIABLE
sub a by a.static;
#endif

Variable-only blocks may contain OpenType feature variations. These restrict substitution and positioning rules to a specific region of the designspace. Define a feature variation by writing the condition keyword followed by the axis ranges to which the code following the condition should be limited:

#ifdef VARIABLE
condition 600 < wght < 900;
sub dollar by dollar.alt;
#endif

Axis ranges are written as the axis tag bounded by a lower and upper limit. Write a less-than sign (<) between the limit value and the axis tag. Note that, although the less-than sign is written for both the lower and upper limit, the lower limit actually behaves as if a less-than-or-equal sign (≤) was used. An axis range can specify both a lower and upper limit, or only one of the two.

A condition can be restricted to multiple axis ranges. Separate them with a comma. The code following the condition is used only if all specified axis ranges match.

#ifdef VARIABLE
condition 600 < wght < 900, 70 < wdth < 90;
sub won by won.boldcondensed;
#endif