Extract from Master Wilhelm von Schlüssel, Laurel King of Arms letter dated July 30, 1981
The rank that I have decided to add is that of Herald Extraordinary. This is a rank in use in England today, whenever they create a Herald's post for some occasion that is not to become a permanent position on the-College of Arms' roster. The rank of Herald Extraordinary shall be permanent so long as the holder continues to remain active in SCA heraldry. It shall fall in rank below a full Herald but above a Pursuivant. Each Herald Extraordinary shall have a title that is his/her own personal title that s/he shall hold so long as s/he remains active. If s/he should retire from the SCA, the title shall retire with her/him and shall not be used again by anyone else. Such titles must still clear my office. Kingdom Principal Heralds are responsible for elevating heralds in their kingdom to this rank, as they are responsible for all other ranks within their kingdom. This rank is reserved for those heralds who have greatly served the College of Heralds and/or the College of Arms and have achieved the highest level of competence in heraldry. Such a rank shall have no fixed duties, unless such shall be agreed upon by the holder and the Kingdom Principal Herald, but instead the holder of the rank shall be a senior member of the College who shall lend heraldic expertise as s/he sees fit.
refer to Caid wiki. http://caidwiki.org/index.php?title=Personal_Heraldic_Title