Every proposal has one. A page near the back listing what we've assumed, what's excluded, what we're expecting the other side to provide. It is the least-read page in the document, right up until it becomes the only page anyone is looking at.
Early on I wrote that page defensively. Cover yourself. List everything that could conceivably go wrong so that when it does, there's a line you can point at.
That is the wrong instinct, and it produces a page nobody can use. Forty assumptions is not a boundary, it's noise, and a buyer skims it exactly as fast as you'd expect.
The version that works is shorter and more specific. Three or four things that would genuinely change the shape of the work if they turned out to be untrue. Access being available when we said. The environment matching what we were shown. Somebody on their side being able to make decisions inside a week.
Written like that, it stops being a legal shield and starts being a conversation. Sometimes an uncomfortable one, which is the point. If the customer reads "somebody available to make decisions within a week" and goes quiet, you have found the risk before it costs anybody money.
The assumptions page is not where you protect yourself from the project. It's where you find out whether the project is the one you think it is.