In Code Set Administration, there is an "upload" option but no "download" option in the toolbar. This must have been an accidental oversight. I discovered I can right click on any line item, and it appears there: "Download CSV". This downloads the whole code set as a CSV, not just the right-clicked item. For the benefit of everyone who has not discovered the secret workaround, please add the button up the top.

The user needs to be able to download a CSV, make changes, and then re-upload it. Otherwise bulk editing cannot happen.