We have a subject divided library, highly centralized with but one branch
(our Veterinary Science Section -- a full health science library).  Each
"subject floor" in the main library contains books, per's and reference
desk for the group of subjects covered on that floor (sci/tech, socsci,
etc.).  All Per's, bound and unbound, in microform or paper, are shelved
together in a separate sequence from the circulating material (we don't
circulate per's).  There is no separate Per R.R. and no microform room.
Readers and reader-printers are located on each floor where there are
per's.  However, the most current issue received (id'd with a yellow and
black sticker) for the per's on a subject floor are shelved in a separate
sequence of shelving, alphabetically by title (all "back" issues and vols.
are shelved by L.C. call no., I should have said before).  This system
has some advantages (easy to browse the latest issues by title for your
favourite journal), and some disadvantages (cost of having two shelving
sequences, having to "de-sticker" the old current issue when the new one
comes in, cost of all this maintenance, etc.).
Bernard Katz, Head, Humanities and Social Science Division
University of Guelph Library  (bkatz@cosy.uoguelph.ca)