UTF-8 byte offset one past the last character (exclusive end).
UTF-8 byte offset of the first character this feature applies to.
4-character OpenType feature tag, e.g. "liga", "kern", "smcp".
Feature value — 0 to disable, 1 (or higher) to enable/select.
Represents an OpenType feature to enable or disable during text shaping. Tags are 4-character ASCII strings (e.g. "liga", "kern", "smcp", "frac").