Unicode-range
From Webfonts.info
Describes the range of supported characters in the linked webfont. The initial value covers the whole range (U+0-7FFFFFFF) of ISO 10646.
Examples
@font-face { font-family: Webfont; src: url(font.ttf) format("truetype");
unicode-range: U+00??
@font-face { font-family: Webfont; src: url(fontCYR.ttf) format("truetype");
unicode-range: U+04??
h1 { font-family: Webfont,Arial; }
In this example two physical fonts are merged to one virtual font. The first font (font.ttf) only covers Latin1 (U+0000–U+00FF). When the website uses any cyrillic characters the browser will also download fontCYR.ttf and use the characters from this font. When the characters are not in the Latin1 or Cyrillic range, the browser will Arial instead.