# The HTML dialect The HTML `adfToHtml` writes: semantic elements for the nodes and marks below, and the carry element for every other node (`docs/decisions.md` §The HTML dialect). The written form is contract (`docs/decisions.md` §The formats are API). ## Blocks One block a line: blocks are separated by a line feed, and a document holding any ends with one. A document whose `content` is an empty array is the empty string. | ADF | HTML | | --- | --- | | `paragraph` | `

…

` | | `heading`, `level` 1 to 6 | `

…

` to `
…
` | | `blockquote` | `
`, a line feed, its blocks, a line feed, `
` | | `bulletList` | `` | | `orderedList` | as `bulletList` with `
    `; `
      ` for an `order` of 3, a safe integer other than `-0`; no `start` where the list holds no `order` | | `listItem` | its first paragraph straight after `
    1. `: bare where it holds content and no attribute, `
    2. Bolt
    3. `, and as its `

      ` element where it holds an attribute, `

    4. Bolt

    5. `; where other blocks follow, each after a line feed, and a line feed before ``. Otherwise `
    6. `, a line feed, its blocks, a line feed, `
    7. ` | | `codeBlock` | `
      …
      `, the language one token holding no ASCII whitespace (a tab, line feed, form feed, carriage return or space); no `class` where it holds no `language` | | `rule` | `
      ` | | `mediaSingle`, centered, holding one external `media` | `

      …

      `, no `alt` where the media holds none; `

      ` where a link marks it | A container holding no `content` key is its element holding nothing: `
      `, ``, `
    8. `; so is a paragraph or heading, `

      `. For a paragraph, heading, quote, list, list item, code block or rule, every other attribute its type holds (`spec/flavour.md` §Block nodes) is a `data-*` attribute on its element, named as HTML's `dataset` names it, `localId` as `data-local-id`, after the element's own attributes and sorted by name. A string is its value; any other value is its JSON, compact: `
        `, `
        `. A code block's
        `data-*` attributes stand on its `
        `.
        
        ## Inline
        
        | ADF | HTML |
        | --- | --- |
        | `text` | its text, escaped |
        | `em`, `strong`, `code` | ``, ``, `` around the text |
        | `link`, holding `href` and an optional `title` | `` around the text |
        | `hardBreak` | `
        ` | A text node's marks nest in the order its `marks` array lists them, the first outermost: `manual`. Each text node writes its own elements, so two text nodes a link marks are two `
        ` elements. ## Escaping Text and attribute values escape `&`, `<`, `>` and `"` as `&`, `<`, `>` and `"`. Attribute values are double-quoted. Every URL is written as the ADF holds it, whatever its scheme (`docs/decisions.md` §HTML writes a URL as the ADF holds it, whatever its scheme): a link's `href`, an image's `src`, and the `href` of each link a carry element shows. HTML text and attribute values cannot hold a carriage return, which a parser reads as a line feed, a control other than a tab, line feed or form feed, a noncharacter, or a lone surrogate, which UTF-8 cannot encode (WHATWG HTML §13.1.3). A node holding one in a value its element writes rides the carry. ## The carry element A node the sections above cannot write where it stands is the carry element: `
        ` in block position, `` inline, of class `adf-carry`, holding the node's JSON in `data-adf` and showing its content. A carry element may hold a node the sections above write, as the markdown carry may: it reads back as the node it holds, so HTML stored while a node rode the carry reads the same once a later release writes it as its own element. ```html

        Read the CommonMark spec first.

        Then import.

        Ask @Mikael

        ``` - `data-adf` holds the node's JSON compact, keys sorted, as `!adf:carry` does in markdown, its type included, each character HTML cannot hold spelled as a JSON escape, `\u0085`. A document holding no `content` key is the block carry of `{"type":"doc","version":1}`. - The content shown is every text node's text below the node, and what a node holding no text shows in its place: a mention's text, else `@` and its id where it has one; an emoji's text, else its `shortName`; a status's text; a date as `2026-09-13` in UTC; a card's URL, else its name, else the URL its data holds; media's `alt`, else an external one's URL; an extension's text; an expand's title. - In a `
        `, each block's content is a `

        `, and a code block's is `

        …
        `, keeping its line feeds and spaces. Its class is the one the code block's element takes, and it has none where the language is no class token. In a ``, `
        ` parts two blocks'. - A hard break is `
        `, and so is a line feed in text outside a `
        `'s code block. - Text a link marks is `` around it, and a card or an external image is a link to its URL. - An image a link to another target marks shows as portable markdown writes it inline, the link around its `alt`, else the link's target, else its URL, then `image` linking to the image in parentheses: `The moon (image)`. - A node referencing what it cannot show is a note naming it, `(image)`: `image` for media with no `alt` or URL, `link card` for a card with neither URL nor name, an extension's key, else `extension`, for an extension with no text, and `synced block` for a `syncBlock`. A link marking the node goes around the note: `(image)`. - Characters HTML cannot hold are dropped. - A node rides the carry where it holds a mark or a key its element does not write, an attribute its type does not hold as that kind, an empty `attrs`, `content` or `marks`, or a value its element cannot hold: - text holding no character, or a character HTML cannot hold; text holding a mark twice, or a mark with attributes besides a link's `href` and `title`; - an unmarked text node straight after another, which would read back as one; - a link whose `href` or `title` holds a character HTML cannot hold, and an image whose `url` or `alt` holds one or whose link's `href` or `title` does; - an image holding an attribute besides its `center` layout and its media's `type`, `url` and non-empty `alt`; - a heading whose `level` is not 1 to 6, and an ordered list whose `order` is not a safe integer or is `-0`; - a code block holding more than one text node, a marked one, or a language holding ASCII whitespace; - a rule or hard break holding `content`, and a hard break holding an attribute; - a list holding a node that is no `listItem`, or an item holding a mark, text, an empty key or an attribute its type does not hold: the whole list rides the carry; - a `listItem` outside a list, an inline node in block position and a block node inline. - A block carry's JSON nests at most 500 levels less the depth it stands at, an inline carry's at most 500, as in markdown.