Be cautious when downloading these from unofficial forums or "free" IPTV sites, as they often contain expired data or malicious links.
Select to open the folder where AutoCAD stores these files, and paste your file there. 2. IPTV / Set-Top Box (STB) Playlists
They are usually provided by architects or engineers to ensure drawings print with the correct standards. How to "download" and use: Copy the .stb file to your clipboard.
You can download the specific header files directly from the official stb GitHub repository.