$$BF_App

This variable is outbound only for security reasons. You can use the FileMaker JSON functions to place data into $$BF_App and the keys will be merged with the current App model.

When a key is configured with Sync with app, that key is synchronized with the current page model key of the same name.

If the same synced key is returned in both $$BF_App and $$BF_Model in a single hook response, the $$BF_App value is used as the final synced value.

For more information about how the app data model is used by BetterForms, see this page:

App Model