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.
Select to open the folder where AutoCAD stores these files, and paste your file there. 2. IPTV / Set-Top Box (STB) Playlists
You can download the specific header files directly from the official stb GitHub repository.
For software developers, stb is a famous collection of for C/C++.