### 5.4.3 Distances and measurements

Distances in LilyPond are of two types: absolute and scaled.

Absolute distances are used for specifying margins, indents, and other page layout details, and are by default specified in millimeters. Distances may be specified in other units by following the quantity by \mm, \cm, \in (inches), or \pt (points, 1/72.27 of an inch). Page layout distances can also be specified in scalable units (see the following paragraph) by appending \staff-space to the quantity. Page layout is described in detail in Page layout.

Scaled distances are always specified in units of the staff-space or, rarely, the half staff-space. The staff-space is the distance between two adjacent staff lines. The default value can be changed globally by setting the global staff size, or it can be overridden locally by changing the staff-space property of StaffSymbol. Scaled distances automatically scale with any change to the either the global staff size or the staff-space property of StaffSymbol, but fonts scale automatically only with changes to the global staff size. The global staff size thus enables the overall size of a rendered score to be easily varied. For the methods of setting the global staff size see Setting the staff size.

If just a section of a score needs to be rendered to a different scale, for example an ossia section or a footnote, the global staff size cannot simply be changed as this would affect the entire score. In such cases the change in size is made by overriding both the staff-space property of StaffSymbol and the size of the fonts. A Scheme function, magstep, is available to convert from a font size change to the equivalent change in staff-space. For an explanation and an example of its use, see Length and thickness of objects.