A rectangle consists of an array of four values - two pairs of
pairs. The first pair represent the x and y coordinates of the
lower left of the rectangle,.
the second pair represent the x and y coordinates of the upper
right of the rectangle. So [lx, ly, ux, uy].
Although the pairs conventially represent the lower left and
upper right corners, it is in fact legal to represent any
diagaonally opposed corners and.
PDF applications will automatically normalize these when they