FINE bus interface documentation

Does anybody know if there is any detailed documentation for how the FINE bus works out there?  My company manufactures our own device programmer and would like to add support of the FINE bus.  There appears to be zero documentation out there describing how it actually works - byte format, timing, command sequences, etc.  On a particular upcoming project there is no access to the SCI port for programming, so that is not an option.  There are definitely other programmers out there that support programming via FINE, so it must be documented somewhere...

Thanks for any help.