Every CoSy compiler relies on several CoSy-fSDL data specifications, and
especially on an CoSy-fSDL flatform-file <compiler>.fdl.
This flatform-file must be imported to every -specification.
The user can import a flatform-file via command line
option -ff (section 1.4).
If the specification is used only for one compiler, the import can also be
specified in the -specification itself:
This declares that should read an CoSy-fSDL
flat form file with name String and turns on CoSy-fSDL-mode.