HPDC released the HPD Open Standard version 2.1.1 in July 2018, and it become the "effective" version of the HPD Open Standard when it was fully implemented it in the HPD Builder in December 2018. 

Following the Effective Date, all newly published HPDs  need to be compliant with HPD v2.1.1. New HPDs created using the HPD Builder, and any other Standard-compliant automated tool, will automatically be created under HPD v2.1.1.

HPDs completed under previous versions of the HPD Open Standard will remain valid through their existing expiry dates.