Sixth in the order of precedence of letters after name are the following (in order):
(a) Fellowships of learned societies
(b) Royal Academicians and associates
(c) Fellowships, memberships, etc, of professional institutions, associations, etc.
(d) Writers to the Signet
Letters denoting fellowships and memberships of professional institutions are usually restricted to correspondence concerning the particular profession.
As there is no recognised order for placing qualifications awarded by different bodies, a recipient usually places these letters on headed paper, business cards, etc, in order of importance to his particular profession.
Those whose fellowships are by subscription are generally used only in the particular field of interest. For example, if John Smith is a Chartered Engineer and a Fellow of the Royal Historical Society, he would normally be described professionally as John Smith, Esq., CEng. When corresponding on historical subjects, however, he would normally be described as John Smith, Esq., FRHistS. If both series of letters are placed after his name, it is usual to place first those appropriate to the particular function or subject that is being addressed.