# Fields and anchors (/docs/sign/fields-and-anchors)

Every signer needs at least one `signature` field. Fields go on a document's page, in **PDF points
from the top left of the page as displayed** (rotation and crop box applied); uploaded documents
list each page's size in `pages`.

```ts twoslash
import type { SignFieldInput } from "coss";
// ---cut---
const fields: SignFieldInput[] = [
  // By position: page 2 of the first document.
  { type: "signature", document: 0, page: 2, x: 72, y: 640, width: 180, height: 40 },
  // By anchor: over every occurrence of this text in the documents.
  { type: "date_signed", anchor: "{{date:signer_1}}" },
  { type: "text", anchor: "{{text:title}}", width: 160, label: "Your title" },
];
```

## Anchors [#anchors]

Write anchors into your documents as text, like `{{signature:signer_1}}`: `{{<type>:<key>}}` with
letters, digits, `_` and `-` in the key. White text is fine: coss.com finds anchors in the PDF's
text, not its colors. A field given by `anchor` covers each occurrence (`width`, `height`,
`offset_x` and `offset_y` adjust it); an anchor no document has is refused (`invalid_fields`).
Uploading a document returns the anchors found in it.

## Field types [#field-types]

| Type | Filled with |
| --- | --- |
| `signature` | The signer's adopted signature (typed or drawn). |
| `initials` | Their adopted initials. |
| `date_signed` | The date they signed (UTC). |
| `name`, `email` | The signer's name and email. |
| `text` | What they type (at most 1,000 characters), or a template's merge field. |
| `checkbox` | Checked or not; a `required` checkbox must be checked. |

Fields are `required` unless you say otherwise; a signer can't finish with a required field
empty.