The three tiers of attribute

Attributes are written key:value. But the key is not free.

Which keys may be written is set by a ledger. A key that is not in the ledger and carries no namespace is the error ATT03.

/L1/a carries nmae:, which is not in the ledger (check the spelling, or add a namespace if
the value is only carried — e.g. acme.nmae:居室)

That line exists to keep "not looked at" distinguishable from "looked at and fine". With keys unguarded, heigh:2400 silences the height invariant, sit:1 silences the site check and stiar:N silences the vertical circulation — each of them while check stays green. koyu does not keep a state in which what you wrote does not take effect and the file is green.

How a line is spelled (where the : falls, how values are typed, what a repeat does) is in how a line is read. This page is about which keys go where, and what happens to the values.

The three tiers

Tier	Examples	How core treats it
Structure	the path, the type, the region, the level, the other end of a relation, type t air edge w at hinge swing d x y	Always read. If it is broken the file is not read at all — it stops on the spot
Interpreted	h use road daylight site area style ceiling uid name stair riser …	Read. The ledger defines the range of values, and a value outside it produces a diagnostic
Carried	spec fire sound floor sill, and any namespaced key	Not read. Carried, nothing more

Structure keys do not survive as attributes. type:, t:, air:, edge:, w:, at:, hinge:, swing:, d:, x: and y: are lifted into fields of the element as the file is read, and their values are checked right there. So they never appear as ATT01 or ATT02 — a non-numeric t: stops earlier, with t is written as a positive number.

Carried values cannot be looked at. spec:RC, fire:60 and sill:800 are carried and given no meaning. What a wall is made of is a value of the thing-name key (spec); it is not a reason to add a boundary type.

The ledger lists what may be written, not what core reads

Being in the ledger does not mean core reads the key. spec, fire, sound, floor and sill are carried-tier words that are in the ledger — they are listed so that a settled meaning does not get two spellings, and their values are not interpreted.

Conversely, a key that is not in the ledger may still be written if it carries a namespace.

space /L1/a room X1..X2 Y1..Y2 acme.sensor:23 bems.temp:22.5 survey.measured:2026-03-11

A namespace is spelled starting with a lowercase letter and containing at least one dot-separated segment ([a-z][a-z0-9_-]* followed by one or more .[a-z0-9_-]+).

Written	Result
acme.sensor:23	carried. core gives the content no meaning whatever
bems.temp:22.5	the same
Acme.sensor:23	ATT03 — a key starting with a capital is not read as a namespace
acme.Sensor:23	ATT03 — segments take no capitals
sensor:23	ATT03 — no dot
nmae:居室	ATT03 — a misspelling of name. This is the case the rule exists for

core holds no rule about the inside of a namespace, not even how to split it. One dot anywhere makes it carried — that is the whole rule.

Being able to write anything with a namespace is not the same as it meaning something. acme.uid: can be written, but it is carried, and it does not give the space an identity.

The three shapes a value check takes

Interpreted values that do not match the type the ledger sets become diagnostics. A value that was written and not interpreted is never quietly dropped to a default.

Code	What it says	Example
ATT01	a key requiring a positive number got a non-number, zero, or a negative	h on /L1/a is written as a positive number: h:0
ATT02	a value outside a fixed vocabulary	ceiling on /L1/a is one of 0 / 1: ceiling:2
ATT03	a key not in the ledger and not namespaced	see above

A few keys are guarded by their own diagnostics — daylight by DAY01, the direction of a vertical circulation by RUN02, form by RUN05.

daylight is either 1 (in scope for the daylight check) or 0 (out of scope): /L1/b carries daylight:yes
site on zone /L1 is one of 0 / 1: site:yes
style on door (/L1/a | /L1/b) is one of hinged / sliding / auto: style:swing
turn on /L1/b is one of R / L: turn:X

The ledger, element by element

The ledger is closed per element. uid may be written on space and zone and nowhere else — on a boundary it is ATT03.

space

Key	Tier	Value	Meaning
level	structure	a level name	states the level explicitly. Defaults to the first path segment
w	structure	a positive integer in mm, or rest	the dimension of a band member. Cannot be written on a space outside a band
h	interpreted	positive number, mm	ceiling height. Defaults to the level's h
use	interpreted	free	the axis of aggregation. Inherited from a zone
road	interpreted	positive number, mm	the width of an exterior — the mark of a road. Read when frontage is derived
daylight	interpreted	0 / 1	declares whether the daylight question applies
ceiling	interpreted	0 / 1	0 means no ceiling is built
uid	interpreted	an opaque token	persistent identity across renames. Not digits alone, no whitespace
name	interpreted	free	display name
stair ramp escalator	interpreted	N / E / S / W	a vertical circulation. The value is the direction of travel going up
lift	interpreted	1	a lift. It has no direction
form	interpreted	straight / return	whether the run turns back
turn	interpreted	R / L	which way it turns
entry	interpreted	positive number, mm	depth of the boarding floor
landing	interpreted	positive number, mm	depth of the intermediate landing
riser	interpreted	positive number, mm	the maximum riser
tread	interpreted	positive number, mm	the target tread
lane	interpreted	positive number, mm	the width of one unit or lane
slope	interpreted	positive number	the denominator of the permitted slope (slope:6 = up to 1/6)
floor	carried	free	floor finish
spec	carried	free	the name of the thing

zone

Key	Tier	Value	Meaning
name	interpreted	free	display name
use	interpreted	free	the axis of aggregation, inherited by the spaces below
site	interpreted	0 / 1	marks the site aggregation
area	interpreted	positive number, m²	the declared (surveyed) site area, reconciled against the derived one
uid	interpreted	an opaque token	same rule as space

boundary

Key	Tier	Value	Meaning
type	structure	wall / open / stair / shaft / void	the topology of the relation
t	structure	positive number, mm	wall thickness, split about the centreline
air	structure	0 / 1	1 = there is a thing, but it blocks neither air nor light (a railing, a fence)
edge	structure	N / E / S / W	narrows the segments to one face seen from the a side
h	interpreted	positive number, mm	top height of an air:1 boundary
name	interpreted	free	display name
spec	carried	free	the name of the thing (RC, LGS, curtain wall, railing…)
fire	carried	free	fire rating
sound	carried	free	acoustic rating

door / window / asset

A door asset is read against the opening ledger. That is deliberate: there must be no attribute that an asset can carry and an opening cannot.

Key	Tier	Value	Meaning
w	structure	positive number, mm	width. Required (the asset may supply it)
h	structure	positive number, mm	height
at	structure	a 0..1 ratio, or a grid reference	position
edge	structure	N / E / S / W	picks a face when there are several segments
hinge	structure	N / E / S / W	the jamb the hinge sits on
swing	structure	a / b	which side it opens toward
style	interpreted	hinged / sliding / auto	the kind of leaf
name	interpreted	free	unique within the boundary — the key to an opening's identity
sill	carried	free	sill height
spec fire	carried	free

area / seg / column

Element	Structure	Interpreted	Carried
area	(the region is positional)	name	floor spec
seg	w at edge	name	spec fire sound
column	d x y	name	spec

level holds no attribute dictionary

level takes exactly h, slab, pitch and underground; nothing else, not even with a namespace.

level carries undergound:, which is not in the ledger (level reads h / slab / pitch / underground)
level carries acme.x:, which is not in the ledger (level reads h / slab / pitch / underground)

Everything a level holds is a typed field, so there is no attribute dictionary to put a leftover key in. A leftover would vanish without a trace in the machine format — so unless it is refused here, undergound:1 quietly becomes an above-ground storey.

Inheritance and override

There are exactly three paths along which an attribute travels between elements.

use is inherited from zone to space

Only the axis of aggregation is genuinely inherited. The use of the deepest zone whose path is a prefix of the space's path is handed down, and a declaration on the space wins.

koyu 1.0
name 継承の例
grid X 0 4000 8000
grid Y 0 4000
level L1 0 h:2400 slab:150
zone /L1/A name:Aタイプ use:exclusive
space /L1/A/ldk  ldk  X1..X2 Y1..Y2 name:LDK
space /L1/A/hall hall X2..X3 Y1..Y2 name:玄関 use:common

By use: exclusive 16.00 m2 (50.0%) / common 16.00 m2 (50.0%)

/L1/A/ldk received exclusive from the zone without writing it; /L1/A/hall overrode it with its own common.

floor overrides space → area, and spec overrides boundary → seg, over an interval

area and seg are segmentations that are not counted. They carry a region or an interval, and the attributes that differ only there.

space /L1/ldk ldk X1..X2 Y1..Y2 floor:オーク
  area X1..X1+1800 Y1..Y1+1800 name:土間 floor:タイル

boundary /L1/ldk /L1/corridor spec:LGS
  seg w:1800 at:0.5 spec:受付ガラス

This is an override over an interval — not composition, not inheritance. The value of the segmentation is read for its region or its interval, and the parent's value is read outside it. Segmentations affect neither area nor room count nor the graph; only spaces and boundaries are counted.

Nothing else travels

The flow from an asset to an opening looks like an exception. An asset's attributes become the opening's defaults, and attributes written on the opening line override them. That is not inheritance but a reference — a way to keep a bundle of default values in one place. A name inherited from an asset is the name of a type, not a claim about that opening's identity: hanging the same product twice on one wall is ordinary design.

Nor is it inheritance when h falls back from a space to its level. That is a rule of derivation: read the space's h, and failing that the level's. With neither, no shape can be made, and it is SUF01 — see what happens when you write nothing.