This means that if you miss a few updates, make sure to look through the release notes for each update you missed to see if the other folders require an update. Make sure you back up your binds and other custom settings before you do this.
If you have already have a config, or want to remove mastercomfig, delete any configs you may have in Valve, the Valve logo, Steam, the Steam logo, Team Fortress, the Team Fortress logo are trademarks and/or registered trademarks of Valve Corporation.
Console commands can change the FOV to values below & above the slider's range.
It is possible to increase the FOV limit up to 130 using server-side plugins such as this one.
This is because this config is heavily tuned and the commands and values are based on TF2's source code, rather than just experiments, guesswork and trying to understand the vague/non-existent documentation.