[rjwse@aol.com]

I have been using epub format exclusively in the tag editor. When uploading an epub file to Amazon's application Kindle Previewer the epub file is converted to their proprietary format so you can read it on the Kindle Previewer application.
However, calibre has a converter which will convert epub to azw3. The resulting file is called kf8. I would have thought that the purpose of the file being converted from epub to azw3 would be to let you load this file into the Kindle Previewer application so that it does not require conversion from epub to the proprietary format. But, Kindle Previewer does not accept uploading of the calibre-converted azw3, while it will accept the calibre epub file. Am I missing something? Best regards, Pop