> ## Documentation Index
> Fetch the complete documentation index at: https://docs.loft.build/llms.txt
> Use this file to discover all available pages before exploring further.
# Wall
```loft theme={"theme":{"light":"github-light","dark":"github-dark"},"languages":{"custom":["/languages/loft.json","/languages/loft-fragment.json"]}}
wall EXT-1 W1 from (grid.A, grid.1) to (grid.B, grid.1)
```
Wall = **segment carrier + vertical extrusion** (the first
carrier-interface implementer — see "Carrier interfaces" on the index).
`start`/`end`/`mid` are the carrier core; the extrusion contributes
`centerline`/`top`/`base` and the face traces, and refines the carrier
datums' shape to plumb lines.
**Placement:** the line grammar — `from … to …`, or carrier + extents
(`from wall.W1 to wall.W3 at 4' right of grid.A`, `along grid.A`). That is the segment
spelling; curve and surface spellings are reserved for the same slot.
## Parameters
| Word | Accepts | Required | Meaning |
| -------------------------------------------------------------- | --------------------------------------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |
| `width`
`width 8"` | length | type · one of: `width` · `layers`, not both | the assembly width — one layer, all core |
| `layers`
`layers [gyp 5/8", core: stud 3-1/2", gyp 5/8"]` | layers list of material | type · one of: `width` · `layers`, not both | the assembly, left to right in the travel frame; `core:` marks the structural run
each layer's material is a free word today, used as a key by the graphics standard; it becomes a reference into the material vocabulary in the materials era |
| `note`
`note "rated partition"` | text | type · optional | a free-text note on the type |
| `type`
`EXT-1` | a walltype | instance · required | the walltype, leading the statement — its width or layers place the faces |
| `from`
`from (grid.A, grid.1)` | line (direction z) or plane (normal xy) | instance · required | where the line starts: a plan point, or a plane it runs from on a carrier placement
with a carrier clause — the `along`, `left` and `right` rows, read after `to` — `from` and `to` name the planes the line runs between; the clause's offset is a length inside it, not a row |
| `to`
`to (grid.B, grid.1)` | line (direction z) or plane (normal xy) | instance · required | where the line ends: a plan point, or a plane it runs to on a carrier placement |
| `along`
`along grid.A` | plane (normal xy) or line (direction xy) | instance · optional | the datum the line rides — it runs in that plane, or follows that line, between `from` and `to` |
| `left`
`at 9' left of grid.B` | plane (normal xy) | instance · optional | the datum the offset measures from, on the left of travel
spelled `left of`, with the offset before it: `at left of ` |
| `right`
`at 4' right of wall.W2` | plane (normal xy) | instance · optional | the datum the offset measures from, on the right of travel
spelled `right of`, with the offset before it: `at right of ` |
| `justify`
`justify left foc` | `centerline` · `left` · `right` · `core.centerline` | instance · required · default: centerline
**revit-parity** — Revit's Location Line default is Wall Centerline | which plane of the assembly the from/to line holds
a side may add its face word: `foc`/`fos`/`fom` hold the core face, `fof` the finish face — what a bare side already means |
| `flip`
`flip` | flag (the bare word) | instance · required · default: off
**practice** — layers read left→right in the travel frame unless flipped (decision 66) | mirror the layer order across the line |
| `base`
`base level.L1 - 6"` | a level ± offset | instance · required · default: the file's level
**revit-parity** — Base Constraint + Base Offset — the level the wall is placed on; the file's `level` statement, or the unit's one level, is that level (decision 74) | the level the wall stands on, ± an offset |
| `top`
`top level.L2` | a level ± offset or plane (normal z) | instance · one of: `top` · `height`, not both (default: the wall's level's top)
**practice** — a story is a fact about the building, stated once on the level — decision 74 | the level the wall reaches, ± an offset |
| `height`
`height 9'-0"` | length | instance · one of: `top` · `height`, not both (default: the wall's level's top) | the wall's height above its base — the other spelling of `top` |
### Reserved
| Word | Rung | Meaning | Arrives with |
| ------------------ | -------- | --------------------------------------------------------------------- | ---------------------------------------------------------------------------------------------------------------- |
| `function` | instance | what the wall does in the building (Revit's Function) | the wall worksheet's second pass — decided at decision 65(e), not yet a clause |
| `structural-usage` | instance | whether the wall bears, shears, or neither (Revit's Structural Usage) | the structure era |
| `room-bounding` | instance | whether the wall bounds rooms — today every wall does | the furred or decorative wall that must not bound a room; bounding is per story since decision 74 |
| `label` | instance | what the tag prints when it is not the id | a bubble or tag printing text other than the id — the grid's bubble is the one that ships |
| `phase` | instance | the phase this element is created in | the phasing era — phases are an ordered list declared in their own file, and a view looks at the model as of one |
| `demolished` | instance | the phase this element is demolished in | the phasing era — phases are an ordered list declared in their own file, and a view looks at the model as of one |
## Datums
| Datum | Shape | Status | Resolution | Rule |
| ------------------------------ | ------------ | ---------- | ---------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `start` | line (plumb) | core | operational | The declared `from` coordinate, on the justify line. Swap the endpoints and `start` moves with the declaration, dependents following. |
| `end` | line (plumb) | core | operational | The declared `to` coordinate, on the justify line — what perimeter chaining connects to. |
| `mid` | line (plumb) | open (§10) | operational | Midpoint of the drawn line. Ships only if a real layout wants it; referencing it names the open question. |
| `centerline` / `cl` | plane | core | intrinsic | The ASSEMBLY's center plane, transverse normal (`cl` is the field spelling — NCS M5 CL, decision 65; one plane, printed as written). Carrier refs and expressions use it regardless of justify (axis-aligned walls only in v0.2 — a diagonal wall's plane is not x̂- or ŷ-normal). Differs from `core.centerline` on asymmetric assemblies. |
| `core.centerline` / `core.cl` | plane | core | intrinsic | The center plane of the `core:` layers (Revit's Core Centerline — the sixth privileged reference, decision 66). Coincides with `centerline` when the non-core layers are symmetric and on width-only types. Measurable in `past`/`short of`; a `justify core.centerline` hold; expression slots as `centerline`. |
| `fos` / `foc` / `fom` (pair) | plane (×2) | core | geometric (side) | The structural CORE face — ONE plane in three field spellings (face of stud / concrete / masonry unit; NCS M4 §4.2.8.3.1 method 1; decision 65), preserved as written; the spelling that disagrees with the core layer's material is the first *warning* once that severity exists. A pair: in `past`/`short of` the tape picks the face facing the measurement (far for `past`, near for `short of`); in `justify` the side word picks (`justify left foc`). Expression slots need a side and teach (D0327). Type-stable: invariant under finish changes. |
| `fof` (pair) | plane (×2) | core | geometric (side) | The FINISH face (NCS M5 FOF, method 3 — "only when required by the project"; decision 65). The v0 wall's outer faces. Same pair rules as the core face. `ff` is reserved (NCS: finish face *and* far face — held for far face; teaching error). Bare `justify left`/`right` already holds this plane. |
| ~~`.face` / `.core` / `.fow`~~ | — | retired | — | Decision 36's invented spellings, revised forward by decision 65: the field's own words replace them (D0326 teaches `fof` / `fos`·`foc`·`fom`). `.core.centerline` is legal — the bare `.core` is not a plane. |
| `top` | plane | core | intrinsic | ẑ position of the wall's top (from `height`/`top` resolution). Consumable in the wall `top` slot: `wall W2 … top wall.W1.top`. |
| `base` | plane | core | intrinsic | ẑ position of the wall's base (its level's elevation). |
## Roles
`layer` · `profile` · `sweep`