The timebox value is a 42-character (21-byte) hexadecimal value stored as a string. When the hex value is converted to a binary value, its 168 bits each map to a single hour within the week. If a bit is set to 1, its corresponding hour is enabled for the role. If set to 0, its corresponding hour is disabled.
After you define the 168 bits using a hexadecimal value, you can usee the encode_timebox function to convert the value into an internal format that specifies when a role is available to use.