The FontIndex structure specifies a Font record in the file.
ifnt (2 bytes): An unsigned integer. If this value is less than 4, then it specifies a zero-based index of a Font record in the collection of Font records in the Globals Substream. If this value is greater than 4, then it specifies a one-based index of a Font record in the collection of Font records in the Globals Substream. MUST NOT equal 4, and MUST be less than or equal to 1022. SHOULD<168> be less than or equal to 510.
Default font, bold
Default font, italic
Default font, bold and italic
The second section, which is optional, contains Font records for any additional font formatting properties present in the file. For example, the 5th Font record in the file is referred to by ifnt value 5.