Setting up Axes

Define interpolation axes in File → Font Info… → Font → Axes. Click the plus  button next to the Axes heading to add a new axis. An axis has a name, a four-character tag, and a hidden-checkbox.

Click the disclosure  button to pick one of the predefined axes. Choosing a predefined axis also sets its four-character tag field with the respective value. The predefined axes are a combination of the registered OpenType design-variation axes and axes proposed for inclusion in the registry. Otherwise, define a custom axis (also referred to as a private axis) by setting an arbitrary axis name and a custom four-letter tag. The tag of a private axis should use four capital letters (A–Z) as not to collide with future registered axes. For instance, a custom Swash Length axis might use the tag SWLN.

Check the Hidden checkbox to hide an axis in user interfaces. If set, this signals to applications using the font that they should not display controls (such as a slider) for this axis. Hide axes if they are applicable only in specialized software. Applications may or may not respect this option. In most cases, this checkbox should be left unchecked.