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Foundations

Layers is built on a small set of foundational concepts that ensure the schema remains modular, interoperable, and extensible across linguistic theories, annotation formalisms, and data modalities.

This section covers:

  • Design Principles: Ten principles guiding all Layers design decisions: theory-neutrality, stand-off architecture, recursive composition, multimodal support, decentralization, and more.

  • Primitives: The core building blocks shared by all Layers lexicons: objectRef, anchor, constraint, agentRef, annotationMetadata, temporalExpression, spatialExpression, knowledgeRef, featureMap, alignmentLink, and W3C selectors.

  • Flexible Enums: The URI+slug pattern that allows the community to mint new annotation kinds, tag sets, and categories without schema changes.

  • Lexicon Overview: The 14 lexicons organized into core pipeline layers, parallel tracks, integration layers, and a cross-cutting changelog layer, with a dependency graph showing how they compose.