found I had a copy of the actual front 'cover' (actually the sheet is folded to give a long rectangle on obverse used as to identify when stacked in a file box) at top is Maughold + name of parties Article of Marriage - NO mention of Lib Scaccc - at bottom NSS (xd thru )and Maughold O.D. added - O D = old deeds
also checked a random collection of other copies I have of Maughold deeds all have NSS (for north side sales) as per my abbreviated index online (a full index on my CD) - to be honest I can't recall in which index book they are in sequence they fall between Lezayre (which I know is in North index) and Lonan (which is in South)
The Museum stores them in a single box per year - adding the parish and parties names is a check on errors so that having got to the stacks they don't find that you really wanted #82 and not #81.