boundary — the boundary between two spaces
boundary /pathA /pathB [key:value...]
door … / window … / seg … / line … # one level of indentation
boundary is not a line that places a wall. It is a line declaring that a boundary relation exists between two spaces. The wall centerline is written nowhere — it is derived from the allocations of the two spaces.
So a boundary belongs to neither space. It is not owned by /L1/a or by /L1/b; it is a first-class relation joining the two.
Segments are derived, not written
How the segments are found depends on whether each side has a region.
| Case | Segments |
|---|---|
| Both sides have a region | the shared edge — the interval where two collinear edges overlap. An overlap of no length is not a boundary (a single corner point is not contact) |
| Only one side has a region | the remaining perimeter — the outline of the side that has a region, minus every interval facing another space on the same level |
| Neither side has a region | no segment |
A vertical kind (stair / shaft / void) | no segment — vertical boundaries carry no wall |
Collinear segments are merged into one, but only when direction, fixed coordinate and the compass point as seen from the a side all agree. That is why an opening can sit on a single segment even where the wall spans several rectangles.
One relation can split into several segments. A boundary with a space that has no region — the outside, typically — usually splits across all four sides of the room, so placing an opening means picking a side with edge:.
Writing a wall boundary to a space on a different level is an error (BND03). Relations that cross storeys are carried by the vertical kinds.
The five kinds
type: says nothing but topology. No name of a thing goes in it — a railing, a curtain wall and reinforced concrete are all values of spec:.
| type | Direction | Passable | Meaning |
|---|---|---|---|
wall | horizontal (default) | only where there is a door | there is something there |
open | horizontal | always | there is nothing there — a nominal seam in one continuous space |
stair | vertical | yes | the topology shared by stairs, ramps and escalators |
shaft | vertical | no | continuous but not passable (a lift shaft, a pipe space) |
void | vertical | no | the absence of a floor |
Vertical passability is carried by the single word stair. A stair, a ramp and an escalator are all the same relation — "you can pass between these levels" — so the type list does not grow. The difference between the devices is declared on the space (stair: ramp: escalator: lift:), where it acts as a rule for generating form.
Floors are not written. Spaces on consecutive levels are vertically adjacent wherever they overlap in plan, and the default reading of that adjacency is "there is a floor". Only the exceptions are declared, with stair / shaft / void.
koyu 1.0
name 五つの kind
unit mm
grid X 0 4000 8000 11000 13500
grid Y 0 6000
level L1 0 h:2700 slab:200
level L2 3000 h:2700 slab:250
space /L1/hall hall X1..X2 Y1..Y2 name:ホール
space /L1/lounge lounge X2..X3 Y1..Y2 name:ラウンジ
space /L1/st stair X3..X4 Y1..Y2 name:階段室 stair:E
space /L1/ev shaft X4..X5 Y1..Y2 name:EV1F lift:1
space /L2/void void X1..X2 Y1..Y2 name:吹抜け
space /L2/office office X2..X3 Y1..Y2 name:事務室
space /L2/st stair X3..X4 Y1..Y2 name:階段室2F
space /L2/ev shaft X4..X5 Y1..Y2 name:EV2F lift:1
space /out exterior name:外部
boundary /L1/hall /L1/lounge type:open
boundary /L1/lounge /L1/st t:150 spec:RC
door w:900 h:2000 name:階段扉
boundary /L1/hall /out t:180 spec:EW
door w:1200 h:2100 edge:S name:玄関
boundary /L2/void /L2/office t:150 spec:手すり air:1 h:1100
boundary /L1/hall /L2/void type:void
boundary /L1/st /L2/st type:stair
boundary /L1/ev /L2/ev type:shaftkoyu graph reads the web of relations back to you.
/L1/hall (ホール)
〰 open → /L1/lounge
— 1 door → /out (spec:EW)
↕ void → /L2/void
/L1/lounge (ラウンジ)
〰 open → /L1/hall
— 1 door → /L1/st (spec:RC)
/L1/st (階段室)
— 1 door → /L1/lounge (spec:RC)
↕ stair → /L2/stTouching spaces default to a wall
You need not write a boundary at all. Wherever two spaces with regions touch in plan on the same level and no boundary has been declared for that pair, a wall boundary is derived. This is the horizontal counterpart of the vertical "default is a floor".
koyu 1.0
unit mm
grid X 0 3600 7200
grid Y 0 4000
level L1 0 h:2700 slab:200
space /L1/a room X1..X2 Y1..Y2 name:A
space /L1/b room X2..X3 Y1..Y2 name:B✔ Consistent — 2 spaces / 1 boundary
Structural consistency only — architectural validity is what koyu validate says, separately"1 boundary" appears although no boundary was written, because of that derivation. And a derived wall has no door, so it cannot be passed.
Cannot reach /L1/b from /L1/aDeclarations exist for the exceptions: to make it open, to make it air:1, to attach attributes, and to hang openings. One declaration anywhere for that pair — even an edge-restricted one — suppresses the derivation. Derived boundaries never appear in the canonical JSON. Green is not grounds for claiming the building can be walked through.
Attributes
| Attribute | Tier | Meaning |
|---|---|---|
type | structure | one of the five words above. Default wall |
t | structure | wall thickness in mm, split evenly either side of the centerline. Left out, drawing uses 100mm |
air | structure | 1 = there is something there, but it blocks neither air nor light (a railing, a fence). Not a statement about passage — a parapet wall is still not passable |
edge | structure | restrict the segments to one compass side N/E/S/W as seen from the a side |
h | interpreted | top height in mm of an air:1 boundary. Default 1100. Anything other than a positive number is ATT01 |
name | interpreted | display name |
spec fire sound | carried | carried and nothing more. spec is the name of the thing, and no tool interprets it |
Structure attributes are lifted straight into typed fields by parse, so they no longer sit among the free attributes of the composed model. Interpreted attributes have their values checked. Carried attributes are never read.
A key that is not in the ledger cannot be written — writing it is ATT03 (error). A value you only want carried takes a namespace containing a dot.
✖ seg (/L1/a | /out) carries finish:, which is not in the ledger (check the spelling, or add a namespace if the value is only carried — e.g. acme.finish:タイル)acme.finish:tile passes. The core never looks at a namespaced key. That boundary is what lets "not looked at" be told apart from "looked at and fine".
air:1 feeds the derivation of semi-outdoor space. A space with a region that meets the outside across an open or air:1 boundary is derived as semi-outdoor, and that reaches at once into the separate line for floor area, the daylight coefficient, where columns stand, and the absence of ceilings and roofs.
Only two things read the a side
boundary /L1/a /out and boundary /out /L1/a are two spellings of the same relation. Area, shape and the position of the segments do not depend on the order.
koyu 1.0
unit mm
grid X 0 6000
grid Y 0 6000
level L1 0 h:2700 slab:200
space /L1/a room X1..X2 Y1..Y2 name:隅切りの室
space /out exterior name:外部
boundary /out /L1/a t:150 spec:RC
line X1,Y2-3000 X1+3000,Y2Rewrite this boundary as boundary /L1/a /out and the area stays at 31.50 m2. The only thing that changes in the canonical JSON is the value of a.
Exactly two things read the order.
edge— it means "the side as seen from the form of a", so swapping a and b flips the compass point- which way a door opens — without
swing:, a door opens into "a if a has a region, otherwise b"
Get edge the wrong way round and the tool says so on the spot.
koyu 1.0
unit mm
grid X 0 6000
grid Y 0 4000 8000
level L1 0 h:2700 slab:200
space /L1/a room X1..X2 Y1..Y2 name:南の室
space /L1/b room X1..X2 Y2..Y3 name:北の室
boundary /L1/b /L1/a t:120 edge:N✖ No shared edge on edge:N: /L1/b | /L1/a (they actually touch on S)Write /L1/a first and edge:N is right; write /L1/b first and it is edge:S. The compass is N=+Y, S=−Y, E=+X, W=−X.
To throw a vertical boundary from storey to storey in one breath, rather than a line at a time, there is stack.
Diagnostics
| Code | Severity | What it says |
|---|---|---|
| REF01 | error | references an undefined space path |
| BND01 | error | a boundary between a space and itself |
| BND02 | error | duplicate boundary for the same pair (identical down to the edge restriction). A wall / open contradiction is caught here too |
| BND03 | error | a wall boundary to a space on a different level |
| BND04 | error | the spaces do not touch — not one segment can be derived |
| BND05 | warning | the same pair carries both an edge-restricted and an unrestricted boundary (the segments overlap) |
| BND06 | warning | the segment has zero length — no edge remains on the perimeter |
| VRT01 | error | a vertical boundary not written between spaces that have both a region and a level |
| VRT02 | error | a vertical boundary between non-adjacent levels |
| VRT03 | error | a vertical boundary between spaces that do not overlap in plan |
| VRT04 | warning | the space above a void boundary is not type:void |
| VRT05 | warning | an opening on a vertical boundary (not interpreted) |
| VRT06 | warning | a seg on a vertical boundary (not interpreted) |
| ATT01 / ATT02 / ATT03 | error | an attribute value is not a number / not in the ledger's vocabulary / the key itself is not in the ledger |
Codes do not appear in the human-readable output of check. Add --json and they do.
To look a code up by cause and cure, there is the list of diagnostic codes.