When I export, every folder has a text file called DEVONtech_storage.
What is this, why is it necessary, what happens if I delete it?
The DEVONtech_storage file contains metadata about the exported material, which is helpful if you want to import it into another database. In fact, if you are planning to do that, DO NOT delete that file.
But you can safely delete the file if your purpose for the export was, for example, to send an exported image file to a friend as an email attachment.
Thanks Bill:
However, I’m confused.
I exported two Folders to the Desktop; each folder contained 3 files.
For one of those Exports, I deleted the metadata text file that was saved to the desktop with the folder, as well as the one that was saved within the folder.
For the other Export, I left the metadata files where they were – one on the desktop, one in the folder.
Then I opened a different database and imported the folders, one at a time. [The metadata files are greyed out, so can’t be selected for import – I just selected the Folder name.]
Both Folders imported with their contents intact.
I can’t see any difference between retaining the metadata file or dumping it. And if it isn’t necessary, it seems kind of a nuisance to have to delete two files for each folder. Is this an option I can turn off?
A bit more discussion:
[1] I always create a target folder in the Finder to receive the export. That keeps the top-level metadata file together with its content (which would be necessary for rebuilding a database, for example). It also prevents files from being scattered all over your Desktop. 
[2] Check the metadata of the two files you experimented with. Look at their Info panels. They should show different creation and modification dates. The file imported without the metadata file will show a creation date and time as of the moment you very recently imported it. The file imported with the metadata file will show the older creation data and time when you first added it to your database. It would also ‘know’ the group location in which it was placed and contain any Comments you might have previously entered.
If you had exported an HTML file, then imported it into a different database, the metadata file would have brought along the URL of the source page. That’s important. If you had exported a PDF import linked to a PDF file, it would show the Path – again, important information.
No, there’s not an option to turn off generation of the metadata file that’s generated using File > Export > Files & Folders. The metadata is critically important for rebuilding a database and can be very important for transferring content between databases.
I did export to a desktop folder (I maintain a very clean desktop).
I tried again:
I selected a Folder in a database. I checked the Info to make note of the origination date, modification date, and path.
I exported the folder from the database to the desktop folder. That folder then contained the export as a sub-folder plus its metadata file. Within the subfolder are four files plus their metadata file.
I opened a different database and asked it to import the subfolder. Again, the metadata files are grayed out and can not be selected for import. After import, I checked the Info on the Folder and it says it was created at the time of import and the path is the desktop folder. In other words, the metadata was irrelevant.
However, if I reimport the folder to the original database, then, yes, the Info shows the original creation date and a new modification date (date and time of import), plus the original path in Finder.
So, when you say the metadata file “can be very important for transferring content between databases”, I don’t get it.
Furthermore, when I exported a single .pdf (no folder), to the same desktop folder that I used before, this export overwrote the metadata file that was already there from the previous export (the Sub-Folder in the Desktop Folder).
When I import that .pdf into a new database, it does come in with its original creation date and path.
However, this generated a somewhat new problem:
In Preferences:Imports, I have “New Notes:In Top or Current Group” and checked “Select and Display new notes automatically”. I assumed “new notes” refers to a new file or folder, but perhaps I am wrong because I could not find this imported pdf. In three window split view I could see the filename, and below, the contents. However, it was not highlighted in the Group hierarchy and Location was blank in the Info panel. I clicked Home and did a Find “within database”. Once again, the filename and contents appeared, but it still didn’t tell me where it was. I had to search manually and finally found it at the very bottom of the Group list.
Something is not quite right about this.