code: function(font) {
      var xml = this.map.font.toXml(font);
      var index = this.index.font[xml];
      if (index === undefined) {
        index = this.index.font[xml] = this.model.fonts.length;
        this.model.fonts.push(xml);
      }
      return index;
    }
docs: ========================================================================= Fonts