How to read a card

Four labels, two colours and one direction. Ten minutes here makes the other pages considerably faster to use.

The four labels

Depends on

Everything upstream that has to be true before this condition can be true. If this is empty, the card is a root and there is nothing further back to check.

Blocks

Everything downstream that cannot hold while this is false. This is the spine of the site. It is also the label that tells you what a failure here will cost.

Confirm by

A check you can actually perform with what you already have. Never a check that involves opening either published address, because this site does not do that and does not ask you to on its behalf.

Not this

The adjacent idea people confuse the card with. Usually a stronger claim than the card is making.

The two colours

Olive marks the upstream direction: dependencies, and the checks that confirm a condition. Mustard marks the downstream direction: what stops, and what a failure costs. Those meanings are fixed everywhere on the site, including in the callout panels inside card bodies. There is no third accent colour and no colour that means good or bad, because this site does not grade anything.

Walking backwards

The useful direction is backwards, even though the cards are written forwards. You start at a symptom, which is almost never a condition. Nothing loads. The login will not take. The order was rejected. A symptom is a place where a false condition finally became visible, and the place it became visible is frequently several arrows downstream of where it went wrong.

1. Find the card closest to your symptom.
2. Read its Depends on list and treat every item there as a question rather than a memory.
3. For each one, ask what evidence you have that it is true right now. Not that you did it once. That it is true now.
4. Any item you cannot answer, open it and repeat.
5. Stop when you reach a card you can positively confirm, or when you reach a root.

The three mistakes

Confusing performing a task with holding a condition

The commonest one by a distance. You installed the software, so the software condition feels true. But the condition is about where the file came from, and installing it is not evidence about that. Every card is phrased as a state rather than an action for exactly this reason.

Reading the numbers as a sequence

A1 to H4 is a filing order. The real order is in the arrows and only in the arrows. Some cards in stage A are upstream of cards in stage E, some cards in stage C are upstream of the very last card on the map, and several cards in the same stage have nothing to do with each other.

Stopping at the first plausible cause

If a condition is false, its downstream list predicts what else should be failing. If those other things are working fine, you have probably found something true but irrelevant. Use the Blocks list as a test of your own diagnosis, not just as a description of consequences.

When the map cannot help

This map contains only conditions that you hold. Whether a service exists, whether it behaves as you expect, whether anybody on the other side is honest and whether an address leads anywhere at all are not on it, because they are not yours and cannot be confirmed from here. Read about this site for where that line is drawn, and the consequences index if you want to see the whole cost of every condition in one list.