L. Ron Hubbard issued tons of “Policy Letters.” They are literally a sanctioned addendum of Scientology gospel (regardless of what the Green Volumes say). As this letter’s postscript states:

Adopted as official
Church policy by
CHURCH OF SCIENTOLOGY
INTERNATIONAL

HUBBARD COMMUNICATIONS OFFICE Saint Hill … Wilfried Handl

DEAR IRS AND EVERYONE …
DOES THIS SOUND LIKE A RELIGION TO YOU?