# usnistgov/metaschema#252

Metaschema provides a common, format-agnostic modeling framework supporting schema, code, and documentation generation *all in one*.

Current modeling technologies (i.e. XML Schema, JSON Schema, Schematron) are:

- Uneven in their modeling expressiveness and validation capability;
- Unable to express a single model that applies to all supported formats;
- Bound to specific formats (i.e., XML, JSON, YAML); and
- Time-consuming and labor-intensive when maintain multiple format-specific models.

In addition to these basic challenges, there is a need to:

- Express and validate cross-instance relationships;
- Generate parsing code in multiple programming languages;
- Support lossless content conversion between all supported formats; and
- Maintain format-specific documentation.

To address the challenges above, Metaschema supports automated:

- Code and documentation generation;
- Robust rules-based, format agnostic validation capabilities; and
- Content conversion between supported formats (i.e., XML, JSON, YAML).

Metaschema achieves this with:

- A modeling abstraction that unifies the modeling and validation capabilities of existing schema and validation technologies.
- Tools that automatically generate code, schemas, documentation, and format-appropriate content converters from Metaschema-based models.