Icon file-naming requirements are:
base_name.size.type
where:
size--l (large), m (medium), t (tiny). For more information about icon sizes, see "Icon Size Conventions".
type--pm (color pixmap), bm (bitmap).
For example, icon file names for medium and tiny pixmap icons for a color printer might be ColorPrinter.m.pm and ColorPrinter.t.pm.
Refer to Chapter 14, Creating Icons for the Desktop, for more information on creating icons.