Cascading Style Sheets - HTML and XHTML: The Definitive Guide - page 468

src : url("http://www.kumquat.com/foundry/kumquat-sans") format("type-1"),
local("Lucida Sans") format("truetype", "intellitype")
In this case, the external font is in Type 1 format, and the local flavors
of Lucida Sans are available in both TrueType and Intellifont formats.
Other recognized font formats include truedoc-pfr, opentype, embedded-
opentype, truetype, truetype-gx , and speedo .
8.4.4.4. Advanced font descriptors
In addition to the standard font descriptors, CSS2 supports a number
of more esoteric ones that further refine the defined font. Typical page
designers do not have much need for these descriptors, but more dis-
criminating typographers may find them useful.
The unicode-range descriptor accepts a comma-separated list of Unicode
values, each beginning with U+ followed by a hexadecimal value. You
can specify ranges of values by adding a dash and another hexadecimal
value; the question mark matches any value in that position.
The purpose of the unicode-range descriptor is to define exactly which
character glyphs are defined in the font. If characters used in your doc-
ument are not available, the browser does not download and use the
font. For example, a value of U+2A70 indicates that the font contains the
glyph at that position in the font. Using U+2A7? represents characters in
the range 2A70 to 2A7F, and U+2A70-2A9F defines a broader range. For
the most part, this descriptor is used to restrict the use of special sym-
bol fonts to just those symbols defined in the font.
The units-per-em descriptor accepts a single numeric value defining the
size of the font's em area. This value is important if you specify the val-
ues of other descriptors using em units.
The panose-1 descriptor accepts exactly 10 integer values, separated by
spaces, corresponding to the Panose-1 characterization of this font. De-
fining the actual Panose-1 values is well beyond the scope of this topic;