This document details how MMIF is versioned.

MMIF components

  1. JSON schema (schema hereinafter): a single file, defining JSON syntax of MMIF serialization. Published on our github and included in mmif-python Python package.
  2. CLAMS vocabulary (vocab hereinafter): consists of type hierarchy (H) and a set of annotation types (T). That is, “CLAMS vocabulary” = {H, T} where each member of T is unique and independently versioned (no two or more versions of the same type is allowed to co-exist in one MMIF version), and H is simply a set edges (inheritance relations) between those type nodes. Published at
  3. CLAMS vocabulary annotation types (types hereinafter): members of CLAMS vocabulary. each type definition is published at, where X at the end is the version number. The definition webpage URL (including the version suffix) is also used as IRI for the type in MMIF serialization.
  4. MMIF specification (spec hereinafter): main documentation (a single markdown file) and a set of example files (published at ).
  5. mmif-python SDK (sdk hereinafter, DO NOT confuse mmif-python with clams-python)

How MMIF is versioned

We use semantic versioning with the major.minor.patch version scheme for the MMIF specification.

However, the CLAMS team doesn’t maintain multiple branches for different levels of versions. So the only major/minor versions that get bug fixes and updates, including any changes in MMIF specifications regardless of their significance, are always the latest ones.

schema, vocab, and spec all share the same version number. sdk only shares major and minor numbers with other components, but a version of sdk will ship the latest versions (as of its publication as a software package) of schema, vocab, types as a part of the package.

Version compatibility and app pipeline

CLAMS pipeline means two or more CLAMS apps are chained together to process the same source data. Typically, a pipeline is formed to make use of outputs of one app as input to the next app.

There are two dimensions of version checking process in CLAMS pipelines.

  1. MMIF JSON syntax: As the sdk includes the schema, when a CLAMS app takes an input MMIF, the sdk will check if the input is valid under the schema included in it (If the app is not using sdk, it’s app developer’s responsibility to make sure the input is valid). Hence, MMIF version numbers themselves should play no role in the validation process.
  2. Annotation type versions: each annotation type has its own versioning (not SemVer, just a single integer versions). If an app written to take A_Type/vX as a target to process but sees A_Type/vY in an input MMIF (where X != Y), the app should know there’s possible version compatibility issue when processing the input. However, again, MMIF version numbers should not play any role in the type checking process.

In short, in most cases app developers does not need to worry about MMIF versions when writing a CLAMS app, unless a new version is “breaking” and thus makes an app unusable in pipelines.

What constitute “breaking” changes

As mentioned above, there are two places where version compatibility matters. MMIF JSON syntax (schema), and definitions of types.

  1. breaking changes in the schema: any changes related to any required fields will probably be breaking changes. Required fields in JSON schema usually related to required, additionalProperties, or value conditions such as mixLength/maxLength.
  2. breaking changes in vocab and types: any changes in an individual annotation type will increase the version of itself. However, inside structures of annotation types are not validated by schema, hence app developers need to pay attention to the changes to the types that are relevant to their apps.

When writing an app using mmif-python and clams-python, a developer usually just target at A_Type (version unspecified) and a version is automatically inferred from the types included in the sdk. Then when the clams-python-based app sees an annotation type in the input that does not match the target version, the default behavior is showing warnings and continue processing.

The CLAMS team will try the best to identify possible breakage in a new release of MMIF in the release note.