I wanted to confirm that the following is the latest version of the ARM trusted board boot requirements (TBBR) - https://developer.arm.com/documentation/den0006/latest/
The document from the above link is noted as being a Beta rather than a final release and has not been updated since 2018 (see information below)
Thanks
Rohit
Document number: ARM DEN0006D
Release Quality: BetaRelease Number: 1Confidentiality Non-ConfidentialDate of Issue: 20/09/2018©
Thank you!