be at a fallback.
<br>In case an axis doesn't include predefined positions, it is mandatory to define at least one fallback position. It should be called `Default` and its value should correspond to the `default_value` position of the axis.
* `fallback_only`
- * Describes whether to only use fallback values when presenting to users.
+ * Describes whether to only use fallback values when presenting to users in the UI. Currently, default to `true`, for continuous range axes should be set to `false.`
* `description`
* A description of the axis.