ROLLO. — To the books of antiquity on papyrus paper, and to some medieval parchment documents, the form of a roll (volumen, rotulus) was commonly given, on which texts were written in columns arranged parallel to the length (pages, schedae) for literary works, and in the opposite direction, without column division, for documentary texts. The writing almost always occupied only one side, namely the inner one, while the outer served as a cover.
When one wished to read the book, it was unrolled in such a way that the writing appeared gradually, on a cylinder of wood or bone (umbilicus), whose ends were often tinted or gilded and vaguely inlaid. The act of rolling and unrolling was called plicare and explicare: the book unrolled and read to the end was said to be a liber explicitus (whence the abbreviation explicit at the end of a work which, similarly to the incipit liber in titles, was, in the Middle Ages, taken as a verb and conjugated). The title