OPAC1 is the acronym for «Online Public Access Catalogue», which is a bibliographical database including all the Library Collection entries online. Each entry describes a Library item be it in print (books, maps, journals) or non-print form (cassettes, CDs, DVDs etc).

The A.T.E.I. of Thessaloniki Library uses «Virtua» by VTLS to record its material. The Vectors iPortal WEB - OPAC is a subsystem of the VIRTUA automatic Library management system, which provides access to the Library Collection.

The Library Catalogue search can be launched according depending on author, title, subject, publisher, classification number etc.

Access to the Catalogue as well as search through it is possible via any PC connected to the Internet. Thus, users can trace the desired material even when they are outside the Library.

OPAC potentials:
Collective or Partial search:	The OPAC Search can be conducted either collectively that is, upon a preselected part defined by session filters on: content (bibliographies, dissertations etc.) item language (English, Greek etc.) item location (Main Collection, Branch Library etc.) year of publication
Search Methods: Simple – Advanced	Simple and Advanced search can be conducted through keywords and Bool factors (AND, OR, NOT, NEAR). Moreover, items can be traced according to their position (which departmental Library they are located in), their content (dissertations, indexes etc.), their language (Greek, English etc.) as well as their year of publication (from when to when).
Search History	Users can retrace, modify and reconduct previously conducted search processes.
Search Results	Apart from viewing the searches, users can save either all of them or just selected entries.

Any entry bears the classification number of its item according to the Dewey Decimal Classification System (DDC). This system codifies item subjects by numbers and also determines item positions on the shelves. Items with similar subjects are placed close together so that users can trace them more easily.
Classification numbers are also imprinted upon tags taped on the backs of the books or on any other visible spot when it comes to non-print material. Each classification number denotes the subject and position of an item and thus, constitutes an important element for its tracing.

Apart from the classification number there are also other signifiers like “ΠΛ”, which stands for “Reference material” that is, non-borrowable material used only within the Library. Under the classification number users can find the first three letters of either the author’s name or the book title, which serves for the alphabetical ordering of items the same classification number. The signifiers τ.1, τ.2, etc. denote the volume number of a multivolume work (e.g. an encyclopedia) while the αντ.1, αντ.2, etc. signifiers stand for the number of copies of an item (in case there are more than one, of course).
The Library staff is always at users’ disposal to provide help or answer any enquiries.