DOS(-a-DOS)

   When two books are bound together so that they share one spine, but with their texts printed upside-down in respect to each other, the composite volume is described in the publishing trade as being bound dos-a-dos (literally "back-to-back"). Such a volume has two front covers and two title pages, which the reader can confirm by turning any example upside-down, revealing a second front cover, right way up, and a second text, likewise. Almost always - though not invariably - the format has been used in sf for paperback originals, the two best known mass-market publishers to have done this being ACE BOOKS in their Ace Doubles series and TOR BOOKS in their Tor Doubles series; some SMALL PRESSES have also engaged in the practice. For the convenience of readers and collectors we use the word "dos" in our book ascriptions in this encyclopedia to designate any edition of a title making up one half of a dos-a-dos twin.A problem arises. Towards the end of their existence as a line, Tor Doubles began to appear with the 2 titles presented sequentially; in strict bibliographical terms these late issues were, in fact, anthologies, just as two earlier series - the Belmont Doubles and the Dell Binary Stars - were, strictly speaking, anthologies. If - as was almost never the case - any of the individual titles reprinted in these series had been originally published as books, the resulting volume would have then been technically describable as an omnibus. But readers do not tend to think of the volumes in these series as being either anthologies or omnibuses; readers (and we) tend to think of them as two titles bound together. We have therefore - in deliberate violation of bibliographical protocol - extended the use of the word "dos" in our book ascriptions to include all titles of publishers' series which "feel" "dos"-like.In this encyclopedia we designate as "dos" all genuine dos-a-dos bindings; we also designate as "dos" all other series-linked bindings that contain two but no more than two titles, each title being named on the cover.

   JC/PN