1671 Microsoft Reader eBook Text (Structured) This eBook format was developed by Microsoft for use with the now discontinued Microsoft Reader software. The format itself is derived from the Microsoft Compiled HTML Help format. 1 Digital Preservation Department / The National Archives 14 Jan 2016 14 Jan 2016 fmt/867 PUID lit File extension 1226 LIT (MS Reader) BOF: ITOLITLS 1 Absolute from BOF 0 0 49544F4C49544C53