When generating output from a Form you can configure the Form to use data retrieved from an external data source.
This enables you to store the data on any server outside of Salesforce for example for economic or security reasons. Note that the generation process speed might decrease.
When creating the data model, you can decide that all or specific sections of the data model will use data from an external source.
During output generation, Docomotion will access the external database, using a service you need to provide, to retrieve the data.