Forms of Address
From the O.T.O. International Bodymaster’s Handbook, (2000 e.v. edition)
Certain forms or styles of address are used in formal correspondence with members of the various degrees of O.T.O. These should be employed when you are writing to someone whose degree is known to you, or writing to an officer whose office is associated with a particular degree, whether you know the officer's actual degree or not. When in doubt, keep it simple: Dear Brother (Sister).
For those addresses in which fraternity is not mentioned, the writer may add “and dear Brother (Sister)” or “and very dear Brother (Sister)” as his or her feelings dictate.
The closing before your signature should be as follows:
Within the V° to X° sign “In the Bonds of the Order,” with such additional expressions of duty as may be suited to the degree of the writer.
For K.E.W. and all lower degrees, use ”Yours Fraternally.”
Additionally, the signature of members of the Supreme Grand Council and higher degrees is prefixed by the triple cross crosslet, or “elevenfold cross” (female members of these degrees may use the triple cross with curved crosslets).
The signature of members of the VII° is prefixed by the triple cross without crosslets.
The Grail Name of members of the VI° is prefixed by the Cross Pattée.
Members of the V° sign with the consonants of the name only.
No form of address, no signature, and no closing should be used within the C.P.I.; within this degree, the writer of the letter should be indicated, if doubt exists, by some allusion in the text.
A superscription should be prefixed to the letter in the following terms:
For X°: “A Petition to His Most Sacred Majesty the Supreme and Holy King ruling in the United States of America (or name of other country) that is in the Sanctuary of the Gnosis.” In the case of a Viceroy, the superscription should be “To His Excellency (name of addressee) Viceroy of (Country) that is in the Sanctuary of the Gnosis.”
For a member of the IX°: “To the Thrice Holy, Thrice Illuminated and Thrice Illustrious (name) IX°.”
For a member of the VIII°: “To the Perfectly Illuminated and Very Illustrious (name) VIII°.”
For a member of the VII°: “To the Very Illustrious Sir Knight (name) VII°.” And so on for the lesser degrees.
It is not strictly necessary for any member below the X° to assume a Magical Title; however, many members prefer to use magical names or mottoes in lieu of their civil names. To avoid confusion, the civil name should always be included in any correspondence addressed to International Headquarters. The Latin “Frater / Soror” is an acceptable alternative to the English “Brother / Sister” when magical names or mottoes are used.
The Latin salutations corresponding to “Dear Brother”, “Dear Sister”, etc. are as follows:
 May be abbreviated to T.H.T.I.T.I.
 The form of address for the XI°, if indeed one exists, is here omitted because of what is said in Liber CXCIV about the Eleventh Degree; since the XI°s are only known as such to each other, the X° and the O.H.O., there is no reason for a form of address for this degree to be generally known.
 The office of “Viceroy,” the head of a national O.T.O. section who was not a full X° but was subject to the X° of another country rather than directly to the O.H.O. seems to have been an ad hoc arrangement used by Crowley while he was still X° under Reuss to put the heads of the other English-speaking sections, who were mostly his disciples anyway, under his control; while it was probably approved by Reuss for a time as an informal arrangement which saved him work, in a 1921 letter to Crowley he specifically repudiates the notion of such an O.T.O. office, which is mentioned neither in the 1917 Constitution or Liber 194.