> ## 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.
# Window
```loft theme={"theme":{"light":"github-light","dark":"github-dark"},"languages":{"custom":["/languages/loft.json","/languages/loft-fragment.json"]}}
window WIN-3050 N1 in wall.W1 at 6' sill 3'-0"
```
A window is the opening interface with one refinement: `sill` is
required, with no default (D0272) — a 0' window sill is never intended,
so the type can't supply it and every placement writes its own, measured
up from the host level (Revit's Sill Height). The operable kinds' selectors
wait for `windowtype`; today's windows keep the contextual jamb lens only.
**Placement:** hosted, as the opening interface's — `in wall.W1 at 6'`; see
[opening](/categories/opening/) for the station vocabulary.
## Parameters
| Word | Accepts | Required | Meaning |
| ------------------------------ | ------------------------- | ------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `type`
`WIN-3050` | a windowtype | instance · required | the windowtype, leading the statement — it fixes or delegates width and height |
| `in`
`in wall.W1` | a wall | instance · required | the host wall |
| `at`
`at 4'` | length | instance · required | the station along the host, from its start — or from a reference (`past` / `short of`), landing `to jamb`, `to jamb.far`, or `to centerline`
the station's reference words are their own rows — `past`, `short` — and the value is a length along the host, so `door.D1.jamb.far + 2'` composes here |
| `past`
`past grid.A` | plane (normal xy) | instance · optional | the datum the station measures forward from |
| `short`
`short of grid.B` | plane (normal xy) | instance · optional | the datum the station measures back from
spelled `short of`: `at short of ` |
| `width`
`width 3'-0"` | length | bound | the clear width — every window has one; the type fixes it or delegates it (`instance`) to each placement |
| `height`
`height 7'-0"` | length | bound | the clear height — every window has one; the type fixes it or delegates it (`instance`) to each placement |
| `u-`
`u-fire-rating "90"` | length or boolean or text | bound | job-specific data, one row per name (`u-fire-rating`): fixed on the type, or delegated (`instance [required]`) and supplied per placement |
| `sill`
`sill 3'-0"` | length | instance · required | the sill height, up from the host level — where THIS window sits, so the type can't supply it |
### Reserved
| Word | Rung | Meaning | Arrives with |
| ----------------------- | -------- | --------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------- |
| `fire-rating` | type | the assembly's fire rating — drawn, not just scheduled (NCS ships nine fire-rating linetypes) | the `duration` value type (`90 min`, `2 hr`) — every parameter value carries units; until then the corpus spells it as text, `u-fire-rating "90"` |
| `hardware-set` | type | the hardware set the leaf carries | the door worksheet — `u-` today, a built-in candidate then |
| `head-height` (derived) | instance | the head's height above the level — sill + height (Revit's Head Height) | the derived-parameter era |
| `kind` | type | which kind of leaf the type is — the category's declaration lists them | a second kind of leaf — the door's and the window's declarations list what is coming (D0242) |
| `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
Inherited from [opening](/categories/opening/): `centerline` / `cl`, `head`, `sill`, `jamb` (pair), `jamb` / `jamb.near` / `jamb.far`.
| Datum | Shape | Status | Resolution | Rule |
| ------------------ | ----- | --------------------- | ----------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `sill` | plane | refinement (required) | intrinsic | The base interface's `sill`, refined: required for every window, with no default — a 0' window sill is never intended, so the opening's level default does not apply here. Still measured up from the host LEVEL (Revit's Sill Height), so a wall's base offset never moves its windows; `0'` is a legal answer when written. |
| *(kind selectors)* | — | reserved | operational | Swing-less windows keep the contextual jamb lens only; the operable kinds (casement/awning/hopper — both mirrorable axes) gain their own selectors when `windowtype` lands, inside the mirrorable-axes schema. |
## Roles
`elevation-swing` · `frame` · `glass` · `opening` · `swing` · `sill-head`