A sheet folded to form 12 leaves or 24 pages.
Although two parallel folds followed by two right
angle folds will produce this gathering, the more
common method is to print the sheet 12 up on each
side, and then cut the sheet into 2 sheets of 8
and 4 leaves. The larger sheet if folded three
times, and the smaller twice, the latter being
insetted. The insetted section may be given a
sub-signature, e.g., B1 or B*, which the binder
notes when binding the book. If the printer
imposes 2 rows of 6 pages (on each side), the
result is known as "long twelves," but if 3 by 4,
"short" or "square" twelves. Where the width of
the leaf is greater than the height, the term
"broad twelves" is used. Also written 12mo or 12.
See also: OBLONG .