HED overview

This document contains the specification for third generation HED or HED-3G. It is meant for the implementers and users of HED tools. Other tutorials and tagging guides are available to researchers using HED to annotate their data. This document contains the specification for the first official release of HED-3G (HED versions 8.0.0-xxx and above.) When the term HED is used in this document, it refers to third generation (HED-3G) unless explicitly stated otherwise.

The aspects of HED that are described in this document are supported or will soon be supported by validators and other tools and are available for immediate use by annotators. The schema vocabulary can be viewed using an expandable schema viewer.


All HED-related source and documentation repositories are housed on the HED-standard organization GitHub site, https://github.com/hed-standard, which is maintained by the HED Working Group. HED development is open-source and community-based. Also see the official HED website https://www.hedtags.org for a list of additional resources.


The HED Working Group invites those interested in HED to contribute to the development process. Users are encouraged to use the Issues mechanism of the hed-specification repository on the GitHub hed-standard working group website: https://github.com/hed-standard/hed-specification/issues to ask for help or make suggestions. The HED discussion forum https://github.com/hed-standard/hed-specification/discussions is maintained for in depth discussions of HED issues and evolution.