CJK Unified Ideographs Extension H is a Unicode block containing rare and historic CJK Unified Ideographs for Chinese, Japanese, Korean, Sawndip, and Vietnamese submitted to the Ideographic Research Group during 2017.
The following Unicode-related documents record the purpose and process of defining specific characters in the CJK Unified Ideographs Extension H block:
Owlapps.net - since 2012 - Les chouettes applications du hibou