The operating manual
Filing rules
How to compute an address, the one decision you make every time you file, and why you will never renumber a card.
Anatomy of an address
The four digits — meaning
Fixed in advance. Sixty-five of them. This is the only place taxonomy lives:1040 is Languages and literature, and always will be. You never invent one.
After the slash — position
Pure address. Answers “where does this card physically sit?” and nothing else. It grows as you file, and it never means anything.
One slash, ever. After it, segments alternate number → letter → number → letter. The type switch is the level marker, which is why no further punctuation is needed: consecutive digits form one segment, consecutive letters form one segment. So 3021/50aa reads unambiguously as 50 → aa.
Computing the next address
- Decide which card the new one hangs off. Call it the parent.
- Look at the parent’s last segment. Ends in a number → append aletter. Ends in a letter → append anumber.
- Take the next unused one. Done — permanently.
Child or sibling
These are not two operations. They are the same operation with a different parent — which is what makes the system runnable at 2am with a card in your hand.
| You want | Parent is | From 1040/9d1a |
|---|---|---|
| Child digs into the card | the card itself | 1040/9d1a1 |
| Sibling continues past it | the card’s parent — drop the last segment | 1040/9d1b |
The question to ask at the drawer: does this continue the card in my hand, or dig into it? Continue → step back one segment and append. Dig in → append directly.
A worked sequence
Seven cards filed behind Rhetoric 1040/9d, in the order they were written. Watch card 6.
Order written
- 1040/9d1Persuasion — HUB
- 1040/9d1aDefinition of a thesis
- 1040/9d1a1Thesis vs. hypothesis
- 1040/9d1bEthos, pathos, logos
- 1040/9d1b1Aristotle, Rhetoric Bk I
- 1040/9d1a2A thesis must be contestable
- 1040/9d2Rhetoric ≠ sophistry
Order in the drawer
- 1040/9dRhetoric — guide card
- 1040/9d1Persuasion — HUB
- 1040/9d1aDefinition of a thesis
- 1040/9d1a1Thesis vs. hypothesis
- 1040/9d1a2A thesis must be contestable
- 1040/9d1bEthos, pathos, logos
- 1040/9d1b1Aristotle, Rhetoric Bk I
- 1040/9d2Rhetoric ≠ sophistry
Card 6 was written sixth and sits fourth. It slid between two cards that already existed, and nothing moved to accommodate it. That is the whole payoff of the alternating scheme — and the reason you must never renumber: a card’s address is the only stable thing other cards can point at.
How each address was derived
| # | Parent | Ends in | So append | Address |
|---|---|---|---|---|
| 1 | 1040/9d | letter d | number → 1 | 1040/9d1 |
| 2 | 1040/9d1 | number 1 | letter → a | 1040/9d1a |
| 3 | 1040/9d1a | letter a | number → 1 | 1040/9d1a1 |
| 4 | 1040/9d1 | number 1 | letter → b (a taken) | 1040/9d1b |
| 5 | 1040/9d1b | letter b | number → 1 | 1040/9d1b1 |
| 6 | 1040/9d1a | letter a | number → 2 (1 taken) | 1040/9d1a2 |
| 7 | 1040/9d | letter d | number → 2 (1 taken) | 1040/9d2 |
Inserting between two cards
There is no between. There is only behind — and behind turns out to be enough, because a child always sits between its parent and its parent’s next sibling.
To place a card between X and the card after it: append to X.Sorting does the rest.
The one genuine limit: nothing can sit between a card and its own first child. That gap is closed, and you will never need it, because sibling order carries no meaning —9d2 is not “prior to” 9d3. When sequence genuinely matters, that is a hub card’s job, not the number’s.
Hub cards, and the other two indexes
If the number cannot tell you what a card says, something else has to find it. Three devices do that work, and they are not interchangeable.
| Device | Holds | Lives | Rewritten |
|---|---|---|---|
| Hub card | A list of addresses on one theme — a switchboard, not prose | In place, at the theme’s centre of gravity | Freely, often |
| Keyword index | Term → one or two entry-point addresses. Deliberately sparse | Its own drawer, alphabetical | Rarely, by addition |
| Bibliographic card | One source, its details, and the cards drawn from it | Its own drawer, by author | Never — append only |
A hub is the one card you are allowed to rewrite, because it holds no thinking — only pointers. That licence is what lets it collapse the drawer separation the four-digit numbers impose: a Persuasion hub can point at 1040/9d, 5080/4p and2020/15 on the same line, and no filing scheme could have put those three together. Keep it a list. The moment a hub contains arguments, it has become a card that belongs somewhere and you have lost your index.
Never
- Never renumber a cardOther cards point at that address, and so does the keyword index. An address is a promise.
- Never use more than one slashThe alternation already marks every level. 1010/1d/1 collides with 1010/1d1, which is Choral conducting.
- Never file at a drawer rootN000/1 is free in all five drawers and still wrong — 454 unrelated disciplines as neighbours, and neighbours are the point.
- Never make the branch taxonomicThe outline reads that way only because it was seeded from a taxonomy. Your own cards will not. Forcing it is the Dewey trap one level down.
- Never wait for the right categoryThere is no right category — only the card this one is talking back to. File behind the nearest anchor and let the hub find it.