# LinkML specification

The LinkML specification has a permanent URL:

* [https://w3id.org/linkml/specification](https://w3id.org/linkml/specification)

Note the specification is hosted on the [linkml-model](https://github.com/linkml/linkml-model) repository.

This specification is aimed at implementers of LinkML tools rather
than general users. It is more formal in its language than this main LinkML guide.

The specification is in the following parts:

1. **Introduction**: general background
2. **Instances**: formalization of what instance data is in LinkML.
3. **Schemas**: the LinkML metamodel and the structure of LinkML schemas.
4. **Derived Schemas**: Inference rules for schemas - for example how [is_a](https://w3id.org/linkml/is_a) is used.
5. **Validation**: Rules for validating instance data given a schema.
6. **Mapping**: Serializing and deserializing instance data to dictionary and graph representations.