Sly literary puzzle masquerading as a novel; If on a Winter's Night a Traveler, by Italo Calvino. Translated from the Italian by William Weaver. A Helen and Kurt Wolff Book. New York: Harcourt Brace Jovanovich. $12.95.

This is a novel about reading and writing that exemplifies what it is talking about as it goes along. Got that? The question comes to mind often -- too often for readers without a taste for literary puzzles -- as Italy's prizewinning Italo Calvino once more sends us a shimmering mirage of fantasy and the everyday.

"Invisible Cities," for example, made a place for itself reminiscent of Marianne Moore's definition of poetry as imaginary gardens with real toads in them. Here were imaginary cities of antiquity with real issues of today in them.

Now the recognizable is buried in the bizarre as Calvino seems to start and break off 10 books in the course of one -- whose left-in- midair title, "If on a Winter's Night a Traveler," becomes part of a sly surprise at the end. The multiple parodistic echoes unfortunately dwell at times on such narrative genres as Arabian Nights eroticism and more recent sex-and-violence, of whose excesses no one needs to be reminded. The act of reading itself is sometimes rather ludicrously suggested in amorous terms. But a greater portion of the book(s) involves other styles and content and a tantalizing evocation of bookishness itself.

Calvino turns readers, not to mention authors, into characters. Just when things get interesting for someone, the story is interrupted: There has been a publishing mix-up; a change of language, a new hero and heroine, a different manuscript, a further twist in a possible conspiracy. Or are all the stories just one story after all?

A delicious episode offers various alternative outcomes when two envious writers virtually coalesce as they try to impress a reader who each believes is smitten with the other's work. Calvino not only lets someone propose that novels could be more quickly read by having a computer break them down into lists of word frequencies; he sets down sample lists to evoke whole novels. He tells tricks of the author's trade and simultaneously shows them in operation, adding his characteristic inventive and arcane detail.

"Is it I who keep changing and seeing new things of which I was not previously aware?" asks a character who finds rereading a book to be like reading a different book for the first time. Or is reading itself a kind of construction with so many variables that the same pattern cannot be repeated?

Another passage speaks of "the mental models through which we live our human events" or, rather, "the mental models through which we attribute to human events the meanings that allow them to be lived."

Got that?

Calvino is jauntily ready to tangle with such questions, and he expects his readers to be, too -- sharing in the infatuation that a denizen of this volume has with "angles of refraction established among shining surfaces variously inclined."