Extents

Pairs are also used to store intervals, which represent a range of numbers from the minimum (the car) to the maximum (the cdr). Intervals are used to store the X- and Y- extents of printable objects. For X extents, the car is the left hand X coordinate, and the cdr is the right hand X coordinate. For Y extents, the car is the bottom coordinate, and the cdr is the top coordinate.

Procedures for working with intervals are found in scm/lily-library.scm. These procedures should be used when possible to ensure consistency of code.