# MDAST Schema ```txt https://ns.adobe.com/helix/pipeline/mdast ``` The Markdown AST is 100% API compatible with the [UnifiedJS MDAST](https://github.com/syntax-tree/mdast) data structure. All [MDAST Utilities](https://github.com/syntax-tree/mdast#list-of-utilities) are compatible and can be used for easy processing of MDAST trees. | Abstract | Extensible | Status | Identifiable | Custom Properties | Additional Properties | Access Restrictions | Defined In | | :------------------ | :--------- | :----- | :----------- | :---------------- | :-------------------- | :------------------ | :------------------------------------------------------------ | | Can be instantiated | No | Stable | No | Forbidden | Forbidden | none | [mdast.schema.json](mdast.schema.json "open original schema") | ## MDAST Type `object` ([MDAST](mdast.md)) # MDAST Properties | Property | Type | Required | Nullable | Defined by | | :------------------------------ | :------------ | :------- | :------------- | :--------------------------------------------------------------------------------------------------------------- | | [type](#type) | Not specified | Optional | cannot be null | [MDAST](mdast-properties-type.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/type") | | [children](#children) | `array` | Optional | cannot be null | [MDAST](mdast-properties-children.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/children") | | [position](#position) | `object` | Optional | cannot be null | [MDAST](mdast-properties-position.md "https://ns.adobe.com/helix/pipeline/position#/properties/position") | | [value](#value) | `string` | Optional | cannot be null | [MDAST](mdast-properties-value.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/value") | | [payload](#payload) | `object` | Optional | cannot be null | [MDAST](mdast-properties-payload.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/payload") | | [depth](#depth) | `integer` | Optional | cannot be null | [MDAST](mdast-properties-depth.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/depth") | | [ordered](#ordered) | `boolean` | Optional | cannot be null | [MDAST](mdast-properties-ordered.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/ordered") | | [start](#start) | `integer` | Optional | can be null | [MDAST](mdast-properties-start.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/start") | | [spread](#spread) | `boolean` | Optional | can be null | [MDAST](mdast-properties-spread.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/spread") | | [checked](#checked) | `boolean` | Optional | can be null | [MDAST](mdast-properties-checked.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/checked") | | [align](#align) | `array` | Optional | cannot be null | [MDAST](mdast-properties-align.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/align") | | [lang](#lang) | `string` | Optional | can be null | [MDAST](mdast-properties-lang.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/lang") | | [identifier](#identifier) | `string` | Optional | cannot be null | [MDAST](mdast-properties-identifier.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/identifier") | | [label](#label) | `string` | Optional | cannot be null | [MDAST](mdast-properties-label.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/label") | | [url](#url) | `string` | Optional | cannot be null | [MDAST](mdast-properties-url.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/url") | | [meta](#meta) | `object` | Optional | can be null | [MDAST](meta-definitions-meta.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/meta") | | [title](#title) | `string` | Optional | can be null | [MDAST](mdast-properties-title.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/title") | | [code](#code) | `string` | Optional | cannot be null | [MDAST](mdast-properties-code.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/code") | | [intro](#intro) | `string` | Optional | can be null | [MDAST](mdast-properties-intro.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/intro") | | [image](#image) | `string` | Optional | can be null | [MDAST](mdast-properties-image.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/image") | | [types](#types) | `array` | Optional | cannot be null | [MDAST](mdast-properties-types.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/types") | | [alt](#alt) | `string` | Optional | can be null | [MDAST](mdast-properties-alt.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/alt") | | [referenceType](#referencetype) | Not specified | Optional | cannot be null | [MDAST](mdast-properties-referencetype.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/referenceType") | | [data](#data) | `object` | Optional | cannot be null | [MDAST](mdast-properties-data.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/data") | ## type The node type of the MDAST node `type` * is optional * Type: unknown * cannot be null * defined in: [MDAST](mdast-properties-type.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/type") ### type Type unknown ### type Constraints **enum**: the value of this property must be equal to one of the following values: | Value | Explanation | | :--------------------- | :------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | `"root"` | The root node, representing a document or section | | `"paragraph"` | A paragraph. Note: standalone \`image\` blocks are often wrapped in a \`paragraph\` | | `"text"` | Plain text | | `"heading"` | A heading with heading level | | `"thematicBreak"` | A section break | | `"blockquote"` | A blockquote | | `"list"` | An ordered or unordered list | | `"listItem"` | | | `"table"` | A table | | `"tableRow"` | A row in a table | | `"tableCell"` | A cell in a table | | `"html"` | Raw HTML embedded in Markdown. Disabled by default. | | `"code"` | A code block | | `"yaml"` | A metadata block. If the block is not at the top of the document, it will start a new section. | | `"definition"` | A definition that can be referenced | | `"footnoteDefinition"` | A footnote | | `"emphasis"` | emphasis (often in italics) | | `"strong"` | strong (often in bold type) | | `"delete"` | deleted content | | `"inlineCode"` | inline code | | `"break"` | A line break | | `"link"` | A hyperlink | | `"image"` | An image | | `"linkReference"` | A pointer to a link | | `"imageReference"` | A pointer to an image | | `"footnote"` | A footnote | | `"footnoteReference"` | A reference to a footnote | | `"embed"` | Content embedded from another page, identified by the \`url\` attribute. | | `"dataEmbed"` | Data embedded from another data source (API), identified by the \`url\` attribute. | | `"section"` | A section within the document. Sections serve as a high-level structure of a single markdown document and can have their own section-specific front matter metadata. | | `"icon"` | An SVG icon, identified by the syntax \`:foo:\` | ## children `children` * is optional * Type: an array of merged types ([Details](mdast-properties-children-items.md)) * cannot be null * defined in: [MDAST](mdast-properties-children.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/children") ### children Type an array of merged types ([Details](mdast-properties-children-items.md)) ## position Marks the position of an AST node in the original text flow `position` * is optional * Type: `object` ([Position](mdast-properties-position.md)) * cannot be null * defined in: [MDAST](mdast-properties-position.md "https://ns.adobe.com/helix/pipeline/position#/properties/position") ### position Type `object` ([Position](mdast-properties-position.md)) ## value The string value of the node, if it is a terminal node. `value` * is optional * Type: `string` * cannot be null * defined in: [MDAST](mdast-properties-value.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/value") ### value Type `string` ## payload The payload of a frontmatter/yaml block `payload` * is optional * Type: `object` ([Details](mdast-properties-payload.md)) * cannot be null * defined in: [MDAST](mdast-properties-payload.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/payload") ### payload Type `object` ([Details](mdast-properties-payload.md)) ## depth The heading level `depth` * is optional * Type: `integer` * cannot be null * defined in: [MDAST](mdast-properties-depth.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/depth") ### depth Type `integer` ### depth Constraints **maximum**: the value of this number must smaller than or equal to: `6` **minimum**: the value of this number must greater than or equal to: `1` ## ordered Is the list ordered `ordered` * is optional * Type: `boolean` * cannot be null * defined in: [MDAST](mdast-properties-ordered.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/ordered") ### ordered Type `boolean` ## start Starting item of the list `start` * is optional * Type: `integer` * can be null * defined in: [MDAST](mdast-properties-start.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/start") ### start Type `integer` ## spread A spread field can be present. It represents that any of its items is separated by a blank line from its siblings or contains two or more children (when true), or not (when false or not present). `spread` * is optional * Type: `boolean` * can be null * defined in: [MDAST](mdast-properties-spread.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/spread") ### spread Type `boolean` ## checked A checked field can be present. It represents whether the item is done (when true), not done (when false), or indeterminate or not applicable (when null or not present). `checked` * is optional * Type: `boolean` * can be null * defined in: [MDAST](mdast-properties-checked.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/checked") ### checked Type `boolean` ## align For tables, an align field can be present. If present, it must be a list of alignTypes. It represents how cells in columns are aligned. `align` * is optional * Type: `string[]` * cannot be null * defined in: [MDAST](mdast-properties-align.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/align") ### align Type `string[]` ## lang For code, a lang field can be present. It represents the language of computer code being marked up. `lang` * is optional * Type: `string` * can be null * defined in: [MDAST](mdast-properties-lang.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/lang") ### lang Type `string` ## identifier For associations, an identifier field must be present. It can match an identifier field on another node. `identifier` * is optional * Type: `string` * cannot be null * defined in: [MDAST](mdast-properties-identifier.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/identifier") ### identifier Type `string` ## label For associations, a label field can be present. It represents the original value of the normalised identifier field. `label` * is optional * Type: `string` * cannot be null * defined in: [MDAST](mdast-properties-label.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/label") ### label Type `string` ## url For resources, an url field must be present. It represents a URL to the referenced resource. `url` * is optional * Type: `string` * cannot be null * defined in: [MDAST](mdast-properties-url.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/url") ### url Type `string` ### url Constraints **URI reference**: the string must be a URI reference, according to [RFC 3986](https://tools.ietf.org/html/rfc3986 "check the specification") ## meta `meta` * is optional * Type: `object` ([Details](meta-definitions-meta.md)) * can be null * defined in: [MDAST](meta-definitions-meta.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/meta") ### meta Type `object` ([Details](meta-definitions-meta.md)) ## title Extracted title of the document `title` * is optional * Type: `string` * can be null * defined in: [MDAST](mdast-properties-title.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/title") ### title Type `string` ## code Icon code `code` * is optional * Type: `string` * cannot be null * defined in: [MDAST](mdast-properties-code.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/code") ### code Type `string` ### code Constraints **pattern**: the string must match the following regular expression: ```regexp :#*[a-zA-Z_-]+[a-zA-Z0-9]*: ``` [try pattern](https://regexr.com/?expression=%3A%23*%5Ba-zA-Z_-%5D%2B%5Ba-zA-Z0-9%5D*%3A "try regular expression with regexr.com") ## intro Extracted first paragraph of the document `intro` * is optional * Type: `string` * can be null * defined in: [MDAST](mdast-properties-intro.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/intro") ### intro Type `string` ## image Path (can be relative) to the first image in the document `image` * is optional * Type: `string` * can be null * defined in: [MDAST](mdast-properties-image.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/image") ### image Type `string` ### image Constraints **URI reference**: the string must be a URI reference, according to [RFC 3986](https://tools.ietf.org/html/rfc3986 "check the specification") ## types The inferred class names for the section `types` * is optional * Type: `string[]` * cannot be null * defined in: [MDAST](mdast-properties-types.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/types") ### types Type `string[]` ## alt An alt field should be present. It represents equivalent content for environments that cannot represent the node as intended. `alt` * is optional * Type: `string` * can be null * defined in: [MDAST](mdast-properties-alt.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/alt") ### alt Type `string` ## referenceType Represents the explicitness of a reference. `referenceType` * is optional * Type: unknown * cannot be null * defined in: [MDAST](mdast-properties-referencetype.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/referenceType") ### referenceType Type unknown ### referenceType Constraints **enum**: the value of this property must be equal to one of the following values: | Value | Explanation | | :------------ | :------------------------------------------------------------------ | | `"shortcut"` | the reference is implicit, its identifier inferred from its content | | `"collapsed"` | the reference is explicit, its identifier inferred from its content | | `"full"` | the reference is explicit, its identifier explicitly set | ## data data is guaranteed to never be specified by unist or specifications implementing unist. Free data space. `data` * is optional * Type: `object` ([Details](mdast-properties-data.md)) * cannot be null * defined in: [MDAST](mdast-properties-data.md "https://ns.adobe.com/helix/pipeline/mdast#/properties/data") ### data Type `object` ([Details](mdast-properties-data.md))