DevonStorage Format for Importing Metadata

I am considering a project to import a large set of documents which I now keep in an SQL database and move those to DT3.

Am I correct that if I wish to import metadata I would need to create Devonstorage files similar to those created when exporting files from DT3? If so, is the format for such a file documented?

It would not be a trivial thing to try and create those files, and likely impossible to to internal values being stored in it.