Ground you are standing on
Four conditions about the machine and the room. Nothing on this map supports them, and almost everything on this map rests on them.
Stage A is the part of the map that has nothing to do with a marketplace. It is about the object in front of you and the space around it. It sits first because two of its four conditions are roots, meaning nothing else on this map holds them up. If a root is false there is nowhere further back to go, and the failure travels forward through everything.
People skip this stage because it is boring and because it does not feel connected to the thing they came to do. The connection is real and it is short. Control of the machine is directly upstream of the browser, the wallet, the clock and the single copy question. Follow four arrows forward from it and you are already at the point where value moves.
What enters this stage
Nothing. That is what makes it stage A. There is no earlier page to send you here, and the conditions here are things you either brought with you or did not. You cannot acquire them by reading. You can only find out whether they are true and then decide what to do about it.
What leaves this stage
Four arrows go out of stage A into stage B and beyond. The browser came from the Tor Project waits on machine control, because installing software you cannot verify on a machine you do not administer is two problems wearing one coat. The client can build a circuit at all waits on the clock. The browser doing this does nothing else waits on the room. And a wallet whose keys are yours waits on both machine control and the single copy question, which is how a stage about furniture ends up upstream of a stage about money.
The shape of the stage
| Condition | Upstream | Directly downstream |
|---|---|---|
| A1 machine control | root | four conditions |
| A2 the clock | A1 | one condition |
| A3 the room | root | one condition |
| A4 single copies | A1 | four conditions |
That table is the honest summary of why this stage is worth ten minutes. A1 and A4 between them are directly upstream of eight other conditions, and indirectly upstream of nearly the whole map. A2 and A3 each carry one arrow, so a failure in either is annoying rather than structural.
Olive on this site always marks the upstream direction: the things a condition rests on, and the checks that confirm it. Mustard always marks the downstream direction: what stops working.
Where the confusion usually lands
Almost every failure that starts in stage A gets diagnosed somewhere else. A clock that is badly wrong produces an error about the network. A machine with management software on it produces nothing visible at all. A room with somebody in it produces a problem you find out about much later, from someone else. That mismatch between where a fault starts and where it shows up is the reason this site is arranged as a graph rather than as a list of things to check.
If you want the general version of that argument, how to read a card sets out what the arrows mean and how to walk them backwards from a symptom. If you want to see how far a stage A failure travels, the consequences index lists every condition with everything that stops when it is false.