Attachments are files stored in Google Drive, owned by the storage account of the library. Attachments are elements of an AODOcs document.
Document attachments are listed in the sidebar of your AODocs document. In Document Management libraries you can also access attachments in the Properties panel, under Attachments.
Documents in Team Folders and Secured folders have exactly one attachment.
A single attachment in a Secured Folder
Documents in Document Management libraries can have no attachments, one or several attachments.
Multiple attachments in a Document Management library
Some actions for managing attachments are available in all types of library. These include previewing attachments, uploading a new version of an attachment, and downloading attachments.
Other actions for managing attachments are specific to Document Management libraries. These include adding new attachments, attaching files by drag and drop, and removing attachments.