# page.cavu.book

> Published by [cavu.page](https://lexicon.garden/identity/did:plc:citulkqjdzbnf7wd5xb6lled)

✓ This is the authoritative definition for this NSID.

## Links

- [View on Lexicon Garden](https://lexicon.garden/lexicon/did:plc:citulkqjdzbnf7wd5xb6lled/page.cavu.book)
- [Documentation](https://lexicon.garden/lexicon/did:plc:citulkqjdzbnf7wd5xb6lled/page.cavu.book/docs)
- [Examples](https://lexicon.garden/lexicon/did:plc:citulkqjdzbnf7wd5xb6lled/page.cavu.book/examples)

## Definitions

### `page.cavu.book`

**Type**: `object`

Book extension object, embedded in a site.standard.publication record as a pass-through `book` property (the Leaflet `theme` pattern). Its presence marks the publication as a book; series publications omit it. The publication's standard fields remain the fallback identity (name = title, description = blurb, icon = square mark).

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `cover` | `blob` | No | Book cover, typically portrait orientation. Share the same blob CID with the frontmatter document's coverImage. |
| `spine` | `array` | Yes | Ordered entries for the site.standard.document records holding the book's content, in reading order. Chunk boundaries are storage artifacts, invisible to the reader; a chunk is usually chapter-sized but not always. |
| `series` | `ref` → `#seriesRef` | No | The series this book belongs to, if any. |
| `listing` | `string` (at-uri) | No | AT-URI of a pub.byline.book record carrying this book's catalog metadata (editions, ISBNs, retailer links, genres). The reading layer stays here; the listing layer stays there. |
| `styling` | `ref` → `#styling` | No | Author presentation preferences for the whole book — the floor of the theme layer. Optional; readers render legibly without it and ignore what they don't understand. |
| `coverAlt` | `string` | No | Alt text describing the cover image, for accessibility. |
| `language` | `string` (language) | No | Primary language of the book's content. |
| `contributors` | `array` | No | Credited contributors (author, translator, editor, illustrator, narrator). Reuses byline.pub's contributor shape: name required, AT Protocol DID optional, so off-protocol collaborators can be credited. The repo owner is presumed primary author unless roles say otherwise. |
| `allowDownloads` | `boolean` | No | Whether readers may download the whole book as a file (EPUB, PDF) rather than only reading it in place. Absent means false — the author opts in. Readers and appviews that offer exports check this flag before generating one; the records themselves are public regardless, so this is a statement of intent, not access control. |
| `pageProgression` | `string` | No | Direction pages progress in paginated and two-page-spread views, mirroring EPUB's spine-level page-progression-direction. Absent means ltr; rtl for right-to-left books (manga). Chiefly meaningful for pre-paginated page.cavu.pages content, where it decides which side of a spread comes first and which way pages turn. |
| `completionStatus` | `string` | No | Whether the book is still being serialized. |

### `page.cavu.book#styling`

**Type**: `object`

Presentation preferences the author sets once for the whole book. Readers apply what they understand and ignore the rest.

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `pageSize` | `string` | No | Printed page size for paginated exports (PDF) and print stylesheets, as a paper name: ISO a4/a5/b5, North American letter/legal, and the book-trade sizes trade (6×9 in), digest (5.5×8.5 in), and pocket (4.25×6.87 in). Absent means the exporter's default (trade). Screen readers ignore it — on-screen pages are a viewport artifact. |

### `page.cavu.book#seriesRef`

**Type**: `object`

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `name` | `string` | No | Series name, denormalized for display without fetching the series publication. |
| `index` | `integer` | No | Position of this book within the series reading order. |
| `publication` | `string` (at-uri) | Yes | AT-URI of the series' site.standard.publication record. |

### `page.cavu.book#spineEntry`

**Type**: `object`

| Property | Type | Required | Description |
|----------|------|----------|-------------|
| `roles` | `array` | No | Structural roles of this chunk, inspired by the EPUB structural semantics vocabulary. Readers use these to find special documents without fetching them — notably `toc`, which marks the document containing the page.cavu.blocks.toc block (the role EPUB's properties="nav" manifest flag plays). Untagged entries are ordinary body matter. |
| `linear` | `boolean` | No | Whether this entry is part of the primary continuous reading flow; absent means true, mirroring EPUB's itemref linear attribute. False for supplementary material (appendices, indexes, notes) that should be reachable from the TOC but skipped when paginating straight through. |
| `document` | `string` (at-uri) | Yes | AT-URI of the site.standard.document record holding this chunk's content. |

## Raw Schema

```json
{
  "id": "page.cavu.book",
  "defs": {
    "main": {
      "type": "object",
      "required": [
        "spine"
      ],
      "properties": {
        "cover": {
          "type": "blob",
          "accept": [
            "image/*"
          ],
          "maxSize": 1000000,
          "description": "Book cover, typically portrait orientation. Share the same blob CID with the frontmatter document's coverImage."
        },
        "spine": {
          "type": "array",
          "items": {
            "ref": "#spineEntry",
            "type": "ref"
          },
          "maxLength": 10000,
          "description": "Ordered entries for the site.standard.document records holding the book's content, in reading order. Chunk boundaries are storage artifacts, invisible to the reader; a chunk is usually chapter-sized but not always."
        },
        "series": {
          "ref": "#seriesRef",
          "type": "ref",
          "description": "The series this book belongs to, if any."
        },
        "listing": {
          "type": "string",
          "format": "at-uri",
          "description": "AT-URI of a pub.byline.book record carrying this book's catalog metadata (editions, ISBNs, retailer links, genres). The reading layer stays here; the listing layer stays there."
        },
        "styling": {
          "ref": "#styling",
          "type": "ref",
          "description": "Author presentation preferences for the whole book — the floor of the theme layer. Optional; readers render legibly without it and ignore what they don't understand."
        },
        "coverAlt": {
          "type": "string",
          "maxLength": 5000,
          "description": "Alt text describing the cover image, for accessibility.",
          "maxGraphemes": 1000
        },
        "language": {
          "type": "string",
          "format": "language",
          "description": "Primary language of the book's content."
        },
        "contributors": {
          "type": "array",
          "items": {
            "ref": "pub.byline.defs#contributor",
            "type": "ref"
          },
          "maxLength": 100,
          "description": "Credited contributors (author, translator, editor, illustrator, narrator). Reuses byline.pub's contributor shape: name required, AT Protocol DID optional, so off-protocol collaborators can be credited. The repo owner is presumed primary author unless roles say otherwise."
        },
        "allowDownloads": {
          "type": "boolean",
          "description": "Whether readers may download the whole book as a file (EPUB, PDF) rather than only reading it in place. Absent means false — the author opts in. Readers and appviews that offer exports check this flag before generating one; the records themselves are public regardless, so this is a statement of intent, not access control."
        },
        "pageProgression": {
          "type": "string",
          "description": "Direction pages progress in paginated and two-page-spread views, mirroring EPUB's spine-level page-progression-direction. Absent means ltr; rtl for right-to-left books (manga). Chiefly meaningful for pre-paginated page.cavu.pages content, where it decides which side of a spread comes first and which way pages turn.",
          "knownValues": [
            "ltr",
            "rtl"
          ]
        },
        "completionStatus": {
          "type": "string",
          "description": "Whether the book is still being serialized.",
          "knownValues": [
            "ongoing",
            "completed",
            "hiatus"
          ]
        }
      },
      "description": "Book extension object, embedded in a site.standard.publication record as a pass-through `book` property (the Leaflet `theme` pattern). Its presence marks the publication as a book; series publications omit it. The publication's standard fields remain the fallback identity (name = title, description = blurb, icon = square mark)."
    },
    "styling": {
      "type": "object",
      "properties": {
        "pageSize": {
          "type": "string",
          "maxLength": 100,
          "description": "Printed page size for paginated exports (PDF) and print stylesheets, as a paper name: ISO a4/a5/b5, North American letter/legal, and the book-trade sizes trade (6×9 in), digest (5.5×8.5 in), and pocket (4.25×6.87 in). Absent means the exporter's default (trade). Screen readers ignore it — on-screen pages are a viewport artifact.",
          "knownValues": [
            "a4",
            "a5",
            "b5",
            "letter",
            "legal",
            "trade",
            "digest",
            "pocket"
          ]
        }
      },
      "description": "Presentation preferences the author sets once for the whole book. Readers apply what they understand and ignore the rest."
    },
    "seriesRef": {
      "type": "object",
      "required": [
        "publication"
      ],
      "properties": {
        "name": {
          "type": "string",
          "maxLength": 2560,
          "description": "Series name, denormalized for display without fetching the series publication.",
          "maxGraphemes": 256
        },
        "index": {
          "type": "integer",
          "minimum": 0,
          "description": "Position of this book within the series reading order."
        },
        "publication": {
          "type": "string",
          "format": "at-uri",
          "description": "AT-URI of the series' site.standard.publication record."
        }
      }
    },
    "spineEntry": {
      "type": "object",
      "required": [
        "document"
      ],
      "properties": {
        "roles": {
          "type": "array",
          "items": {
            "type": "string",
            "maxLength": 1000,
            "knownValues": [
              "cover",
              "frontmatter",
              "toc",
              "bodymatter",
              "backmatter",
              "acknowledgments",
              "appendix",
              "index",
              "glossary",
              "notes",
              "colophon"
            ],
            "maxGraphemes": 100
          },
          "maxLength": 10,
          "description": "Structural roles of this chunk, inspired by the EPUB structural semantics vocabulary. Readers use these to find special documents without fetching them — notably `toc`, which marks the document containing the page.cavu.blocks.toc block (the role EPUB's properties=\"nav\" manifest flag plays). Untagged entries are ordinary body matter."
        },
        "linear": {
          "type": "boolean",
          "description": "Whether this entry is part of the primary continuous reading flow; absent means true, mirroring EPUB's itemref linear attribute. False for supplementary material (appendices, indexes, notes) that should be reachable from the TOC but skipped when paginating straight through."
        },
        "document": {
          "type": "string",
          "format": "at-uri",
          "description": "AT-URI of the site.standard.document record holding this chunk's content."
        }
      }
    }
  },
  "$type": "com.atproto.lexicon.schema",
  "lexicon": 1
}
```