If you are looking for the "paper" or technical specifications behind these codes, several developers have archived the API documentation: M3U8 Xtream Playlist - GitHub

: Tools like the xtream2m3u web interface allow you to input these text-based credentials to generate a downloadable .m3u playlist file, which is more widely compatible with standard media players. Technical Documentation & Resources

If you are looking for documentation or tools to handle these files, the following resources and guides explain how to use and format them. Common Formats for Xtream IPTV Credentials