nbformatminor

nbformatminor is the minor version component of the Jupyter notebook format defined by the nbformat specification. It sits alongside the major version (nbformat) to describe the specific revision within a major release. Together, these fields indicate the syntax, capabilities, and expectations for a given notebook file.

In a notebook’s JSON structure, the top-level keys include nbformat, nbformat_minor, and metadata. For example, a notebook may begin with {"nbformat": 4, "nbformat_minor": 2, "metadata": {}}. The exact numbers depend on the version of the nbformat spec that created or last saved the file. The minor version is updated as the format evolves to accommodate new features or structures without altering the major version.

Minor versions encode incremental changes such as added fields, new metadata, or enhanced feature support. A higher minor value typically signals newer functionality that might not be recognized by older tooling. Within a given major version, minor versions allow the schema to advance while maintaining a level of backward compatibility.

Tooling that works with notebooks—such as readers, writers, converters, and editors—consult nbformat and nbformat_minor to determine parsing and serialization behavior. When saving, libraries may set the minor version to reflect the features actually used in the notebook or to preserve the original minor version for compatibility.

Notes: The nbformat project maintains documentation that maps supported minor versions for each major version. nbformatminor is a small but important detail for ensuring interoperability across Jupyter components and workflows.