Welcome to Project Haystack!

This initial documentation addresses Haystack 4.0 and its suite of new technologies for more advanced data modeling. The work was done under WG 551.

Key concepts for the Haystack 4.0 include:

  • new design for definition of tags and tag sets
  • organization of tags into a taxonomy tree structure
  • symbol relationships between tags for a richer ontology
  • enhancements to the filter query language
  • RDF support

This current documentation is focused only on the major 4.0 features. Eventually we will also include/rework all of the existing documentation into docHaystack as a single document.

Key new concepts to review:

  • Defs: new model for defining tags and tag combinations
  • Namespaces: a new modular design based on versioned libraries
  • Subtyping: organizing all terms into a taxonomy tree based on subtyping
  • Reflection: mapping between dict data and definitions
  • Relationships: more powerful relationship modeling and queries
  • Rdf: prototype support for exporting Haystack data to RDF

This documentation and the definitions is managed in a Mercial repo located at