"One thing you may note also as a matter of etiquette. THE SPIRITUAL MASTER IS ADDRESSED AS HIS DIVINE GRACE, a Godbrother is addressed as His Grace, and any Sannyasin is addressed as HIS HOLINESS."
(67-01-30. Letter: Brahmananda)
Note: Srila Prabhupada speaks about Siksa gurus:
"The GBC should all be the instructor gurus. I AM IN THE INITIATOR GURU, and you should be the instructor guru by teaching what I am teaching and doing what I am doing. THIS IS NOT A TITLE, BUT YOU MUST ACTUALLY COME TO THIS PLATFORM. This I want."
(75-08-04. Letter: Madhudvisa)