what is the nonstop rules for speedruns

You're going to have to provide some more context on this one - what do you mean by "nonstop rules for speedruns"? Are you reading this term posted somewhere?

If your question pertains to a specific game, you should ask the moderators for that game, in the forums for that game rather than the general speedrunning forum.

mario 64 category extensions

You can see the rules on the leaderboard for the game.

If you have any other questions about that specific category, ask them in the correct forum, or in their Discord server. This is the general speedrunning forum, nobody here knows anything about a niche category for a random game.