Short answers, pulled from the story.
The name FOSSIL is an acronym for Fido Opus SEAdog Standard Interface Layer. This title serves as a historical record of the three major players in the early bulletin board system wars. Fido refers to FidoNet, Opus refers to Opus-CBCS BBS, and SEAdog refers to a Fidonet compatible mailer.
The FOSSIL specification was born in 1986 to provide a uniform method for all software to communicate with serial interface hardware. This standard was established to allow software using the FOSSIL standard to communicate using the same interrupt functions no matter what hardware it was running on. The document titled FOSSIL implementation and use was maintained by the Fidonet Technical Standards Committee under the designation FSC-0015.
The built-in support provided by the BIOS was so poor that it could not handle the demands of serious data transfer. As MS-DOS and PC DOS became the prevalent operating systems, the hardware became predominant yet the software layer remained broken. FOSSIL drivers were specific to the hardware they operated on because each was written to fit specifically to the serial interface hardware of that platform.
Two popular DOS based FOSSIL drivers were X00 and BNU which became the backbone of communication for millions of users during the late 1980s and early 1990s. These drivers were not just simple translators but complex pieces of software that managed the flow of data between the application and the physical serial port. A popular Windows based FOSSIL driver called NetFoss was also released as freeware to support the transition to graphical operating systems.
FOSSIL drivers have also been implemented to support other communications hardware by making it look like a modem to the application. Internal ISDN cards that did not use serial ports at all often came with FOSSIL drivers to make them work with software that was originally intended for modem operation only. The driver would present the ISDN card as a standard serial port hiding the complex details of the new technology from the application.