MyST Specification

MyST (Markedly Structured Text) is designed to create publication-quality, computational documents written entirely in Markdown. The main use case driving the development and design of MyST is JupyterBook, which creates educational online textbooks and tutorials with Jupyter Notebooks and narrative content written in MyST.

Overview¶

There are three components that this documentation and repository aims to formalize:

1. the MyST markup language, which is a superset of CommonMark (a standard form of Markdown);
2. the MyST abstract syntax tree (AST), which is the datastructure of a document after it has been parsed, and can be used in transforming and rendering content; and
3. a set of unit-tests that can be used to test implementations of MyST (e.g. in Python and Javascript).

MyST Markup Language¶

MyST is a superset of CommonMark (a standard form of Markdown) and allows you to directly create “directives” and “roles” as extension points in the language. These extensions points are influenced by and Sphinx -- pulling on the nomenclature and introducing additional standards where appropriate. directives are block-level extension points, like callout panels, tabs, figures or embedded charts; and roles are inline extension points, for components like references, citations, or inline math.

MyST Abstract Syntax Tree¶

Fundamentally, the specification for MyST documents can be broken down into abstract syntax tree (AST) node types and their document-level counterparts. The myst-spec AST builds on Markdown AST, or mdast, an intermediate format that in turn builds upon the existing Universal Syntax Tree, or unist spec. unist is used throughout the unifiedjs Javascript community with hundreds of existing transformations, utilities and serializers. unist has a simple format, with a type defining the node optional properties on the node and optional children (a leaf node has a value).

The MyST AST introduces nodes for directives and roles, as well as numerous new features, like admonitions, citiations, and equations, all of which build upon mdast and other existing standards and nomenclature. The MyST AST, like mdast, is serializable to JSON or YAML, and can be effectively shared between projects, languages, and implementations.

MyST Test Cases¶

To validate implementations of MyST spec, a suite of test cases is provided here in myst.tests.json. This file is a JSON list of test cases with MyST markup, MyST AST, and some example HTML (optional). The cases are similar to CommonMark test cases with the addition of the AST representation. The MyST test cases include all the CommonMark examples as well as many MyST specific examples.

Working with the MyST AST¶

This documentation contains all the node types used to construct a MyST document. Conventionally, the AST representation of a MyST document represents the state immediately after parsing. This means, for example, references are not resolved, directive/role structures are still present, etc. You may work with AST nodes by either modifying or adding to them to modify and update the corresponding MyST document, or you may transform and reduce them into a simpler structure to consume in other contexts.