This is a Drupal 8 module that provides list fields that are much more flexible than the core list fields. There are often times when you can't know all of the values you need to provide in a list field up front.
- Allows you to change the list options at any time. Even if the field already contains data.
- Has a whitelist of options that are always available.
- Has a greylist of options that are available only if the field already contains that value. This allows for old values to continue to be used for pre-existing content.