[galaxy-dev] Uploading metadata with file using Web API

Dear All, I have a file path that I'd like to link into Galaxy using a RESTful WEB API call with some additional metadata key-value pairs. How can I do that? I know the /api/libraries/ call respects JSON keys like "folder_id", "file_type", etc. But can I pass to it additional keys and it will know to store them with the file entry? Thank you so much, Oren