This repository contains the HED schema (in wiki format) and the hedtags.org website.
For the HED schema please visit: https://github.com/BigEEGConsortium/HED-schema/wiki
For more general information regarding HED please visit: http://www.hedtags.org
An extensive collection of validation tools in MATLAB and python are available at: https://github.com/VisLab/HEDTools.
You can also find an online HED validator for spreadsheets at: http://netdb1.cs.utsa.edu/hed.