> For the complete documentation index, see [llms.txt](https://docs.fylr.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.fylr.io/for-developers/api/endpoints/api-mask.md).

# /api/v1/mask

Access the **mask** definitions of a datamodel version. Masks project objecttypes to a subset of fields and are the unit through which the frontend renders forms and detail views. `version` can be:

* `HEAD` — the working copy (uncommitted edits). Readable by any authenticated user (`GET` requires only an authenticated user, not `system.datamodel`).
* `CURRENT` — the most recently committed version. Resolved server-side; equivalent to the highest committed number.
* a positive integer pointing at a specific committed version.

### `GET /mask/{version}` — Retrieve all masks for a datamodel version.

{% openapi src="/files/kfiDjhyZfEICNBmt5f49" path="/mask/{version}" method="get" %}
[fylr-openapi.yml](https://4100607288-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FAdRFzQASDY2Elfdm3wXW%2Fuploads%2Fgit-blob-d5aceac1c99d5aa0b623bea061400efbac147a8d%2Ffylr-openapi.yml?alt=media)
{% endopenapi %}

### `GET /mask/{version}/{mask}` — Retrieve a single mask of a datamodel version.

{% openapi src="/files/kfiDjhyZfEICNBmt5f49" path="/mask/{version}/{mask}" method="get" %}
[fylr-openapi.yml](https://4100607288-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FAdRFzQASDY2Elfdm3wXW%2Fuploads%2Fgit-blob-d5aceac1c99d5aa0b623bea061400efbac147a8d%2Ffylr-openapi.yml?alt=media)
{% endopenapi %}

### `POST /mask/HEAD` — Write masks into the working datamodel (`HEAD`).

{% openapi src="/files/kfiDjhyZfEICNBmt5f49" path="/mask/HEAD" method="post" %}
[fylr-openapi.yml](https://4100607288-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2FAdRFzQASDY2Elfdm3wXW%2Fuploads%2Fgit-blob-d5aceac1c99d5aa0b623bea061400efbac147a8d%2Ffylr-openapi.yml?alt=media)
{% endopenapi %}


---

# Agent Instructions
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## Querying This Documentation
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Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.fylr.io/for-developers/api/endpoints/api-mask.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
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Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.