[Haskell-cafe] Cabal: other-modules necessary?

Hi The cabal user guide says (in section 6.2.12): "Every module in the package must be listed in one of other-modules, library:exposed-modules or executable:main-is fields." However, I only get a warning message, when I comment out the other-modules field in my .cabal file. The program compiles. This is the message: <no location info>: warning: [-Wmissing-home-modules] These modules are needed for compilation but not listed in your .cabal  file's other-modules: Hsskripte Sicherung SicherungAktionen Text Wahl Zeit Is it really necessary to specify all the imported modules? If so, why does the program compile? Can that warning message be turned off? Apart from that, I'm happy with cabal. :-) Cheers, Volker