level — levels

level L1 0 h:3600 slab:600
level L4..L10 11000 pitch:3000 h:2500 slab:450
level R 30200 slab:500

level <name> <z> [h:] [slab:] [pitch:] [underground:] gives a name to a floor height. This is the only place in the notation where z is written: a space has no height of its own and takes it from the level it belongs to.

Positionals

Position	Meaning
name	The level's name. Used as the first segment of a space path (/L1/hall)
z	The floor level in mm. May be negative

The name is a free word, but a range declaration is distinguished from a single one by its spelling — a name containing .. is read as a range.

z is a number in the same coordinate system as the grid, and where the origin sits is your choice. The order of levels is the order of their z, not of their names.

Attributes

Four keys may be written on a level, and that list is closed.

Key	Value	Meaning
h:	positive number, mm	The base ceiling height — the default for spaces on this storey
slab:	positive number, mm	Slab thickness. The floor slab is generated downward from this level's FL
pitch:	positive number, mm	The storey height of a range declaration. Only on a range
underground:	0 / 1	Declares that the level is below ground

A key outside the ledger is a syntax error rather than a diagnostic. A level carries no attribute bag — all four keys are lifted into typed fields, and a leftover key has nowhere to live. Dropping it silently would let a storey spelled undergound:1 become an above-ground storey without a word.

grid X 0 3600
grid Y 0 4000
level L1 0 h:2400 slab:150 undergound:1
space /L1/a room X1..X2 Y1..Y2

✖ levelkey.muro:line 3: level carries undergound:, which is not in the ledger (level reads h / slab / pitch / underground)

On every other element an unknown key becomes the diagnostic ATT03; the level alone stops earlier, in the parse.

h: — the base ceiling height

h: is the default ceiling height for spaces on this storey. A space's own h: wins over it.

With neither, the ceiling height cannot be determined, and there is no height to extrude a ceiling or a roof to. That is an error, not a warning.

The ceiling height of /L2/a cannot be determined (neither the space's h: nor level L2's h: is there)

SUF01 reports the spaces whose ceiling height is undetermined. Voids (void), the outside (exterior) and semi-outdoor spaces have no ceiling, so they are not subject to it.

slab: — the slab thickness

slab: is the thickness of the floor slab, and there is no operation that places a floor — declaring the thickness is declaring the floor. The slab is generated from z - slab up to z.

Omit it and not one floor is generated on that storey. The form is still determined, so this is a warning.

Level L2 has no slab:, so not one floor is generated on this storey

Nothing is said about a level carrying no space that could have a floor — there is no missing floor to report.

slab: eats into the headroom of the storey below it, as the floor of the storey above. The storey height is shared out between the lower storey's ceiling height and the upper storey's slab.

$ npx tsx src/cli.ts levels lv.muro
R	z:15000	slab:500
L4	z:11200	h:2700	slab:400
  ↑ storey height 3800 = ceiling 2700 + slab 500 + 600 left over
L3	z:7800	h:2700	slab:400
  ↑ storey height 3400 = ceiling 2700 + slab 400 + 300 left over
L2	z:4400	h:2700	slab:400
  ↑ storey height 3400 = ceiling 2700 + slab 400 + 300 left over
L1	z:0	h:3600	slab:600
  ↑ storey height 4400 = ceiling 3600 + slab 400 + 400 left over
B1	z:-4200	h:3600	slab:600
  ↑ storey height 4200 = ceiling 3600 + slab 600

When the ceiling height plus the slab above exceeds the storey height, HGT01 is an error.

Range declarations — level L4..L10

level L2..L4 4400 pitch:3400 h:2700 slab:400

A name of the form <prefix><digits>..<prefix><digits> expands into an arithmetic run of levels, at z + pitch × k.

Rule	Error
The prefix is the same at both ends	Cannot read the level range: L1..M3
The numbers ascend	Cannot read the level range: L3..L1
pitch: is required	A level range requires pitch: (the storey height in mm): L1..L3
pitch: only on a range	pitch is available only on a level range declaration (L?..L?)

h:, slab: and underground: are applied identically to every level in the expansion. Where the storey height changes, cut the range and write several lines.

Duplicates and equal z

Declaring the same level name twice is an error.

✖ lvdup.muro:line 4: Duplicate level: L1

Two differently-named levels at the same z are the error LVL01 — which one is above the other is undetermined, and the storey height between them is zero.

underground: — being below ground is declared

level B1 -4200 h:3600 slab:600 underground:1

underground:1 declares that the level is below ground; the value is 0 or 1.

It is never inferred from the sign of z. Ground level is a fact about the site; a negative z is a fact about where the origin of the coordinate system was put. Put the origin on the second basement floor and the basements have positive z; put it on the pre-cut ground and above-ground storeys can be negative. Two different facts, written separately.

A wall against earth is carried by neither the boundary's type nor an attribute of it, but by the boundary's spec: (spec:RC土圧壁). The topology of a boundary is the same above and below ground.

underground is emitted into the canonical JSON only when true.

$ npx tsx src/cli.ts json lv.muro
  "levels": {
    "B1": {
      "z": -4200,
      "h": 3600,
      "slab": 600,
      "underground": 1
    },
    "L1": {
      "z": 0,
      "h": 3600,
      "slab": 600
    },

A level with no spaces

A level that carries no space at all is a legitimate declaration. The roof is the usual case, and it acts as the upper bound of the topmost storey's height check.

grid X 0 6000
grid Y 0 8000
level L1 0 h:3600 slab:600
level R 3800 slab:500
space /L1/hall hall X1..X2 Y1..Y2

✖ roof.muro:line 5: /L1/hall collides into the floor above: ceiling height 3600 + R's slab 500 = 4100 > storey height 3800

Delete level R and the same file turns green — a ceiling height with nothing above it has nothing to be reconciled against. Declaring the roof is putting the top storey's height into the arithmetic.

Declare it before you use it

A level has no effect on lines above it. The first segment of a space path is matched against the levels declared so far, so a level written further down arrives too late and the space is left with no level.

grid X 0 3600
grid Y 0 4000
space /L1/a room X1..X2 Y1..Y2
level L1 0 h:2400 slab:150

$ npx tsx src/cli.ts check levellate.muro --json
[
 {
  "code": "SUF02",
  "severity": "error",
  "message": "/L1/a has a region, but its level cannot be determined (give it at the head of the path or with level:)",

The same holds for the level: attribute, a column's level range, stack, and a level span in a path: only a declared level can be named. An undeclared one stops with Undeclared level: level:L9.

Order is z order

Everything about above and below is decided by z, and the spelling of the name plays no part. A level span in a path, /B1..M2/a, expands over the declared levels between the two z values, in ascending z — prefixes need not agree.

grid X 0 3600
grid Y 0 4000
level B1 -3000 h:2400 slab:150
level L1 0 h:2400 slab:150
level M2 3000 h:2400 slab:150
space /B1..M2/a room X1..X2 Y1..Y2

$ npx tsx src/cli.ts stats sp2.muro
B1
  /B1/a	a	room	14.40 m2
  Subtotal 14.40 m2
L1
  /L1/a	a	room	14.40 m2
  Subtotal 14.40 m2
M2
  /M2/a	a	room	14.40 m2
  Subtotal 14.40 m2
Total 43.20 m2 (indoor floor area)
  room: 43.20 m2

Overriding under composition

A level is defined once across all layers. Changing a declared level's values from another layer is over level, and only h / slab / underground can be rewritten (pitch is an input to the expansion, so after expansion there is nothing to point at). The strength rules are in over / drop.

Surfaces come from the level

Floors, ceilings and roofs have no vocabulary of their own, because slab: already declares the floor and h: already declares the ceiling.

• Floor — generated under every space on a storey that carries slab:, except voids and the outside.
• Ceiling — hung at the height that h: fixes. Not in voids, the outside, semi-outdoor spaces, or vertical circulation.
• Roof — laid over whatever is not covered by a space on any level above. Put a penthouse on a podium and the podium roof appears without being written.

A room with no ceiling — an exposed soffit — is declared space-side with ceiling:0. See space.