Damocles will be the first to disagree with this, and though I respect his divinity, I do not agree at all that there are no rules for challenges, we, as players, have always agreed to these things, and only the idiots of avalon would not follow them. They even stop challenging those that can kill them because they can't win without breaking these ancient rules.
In the past and still holding true for most People of Honor.
You shan't Fight in city staves... Run to a city to buy food potions armour whatever fine, your enemy can chase you, but you shouldn't stay in the city staves.
Don't use a non steed CCC. The new changes to unicorn make this especialy valid.
The fighters have the right to ask third parties and their entourages to leave even though these people want to watch.
Can't run to temples and stockrooms.
Let me see, what else. nothing I can think of. These are pretty simple arn't they? 3. Easy number to grasp, even for such a slow, old, soldier like me.
Written by my hand on the 5th of Midwinter, in the year 1154.