o use the datebook-algorithm for timestamps too (implemented, untested)

 o prepare for national versions (unimplemented)

 o use the pilot's preferences for the format of the log-files (unimplemented)

 o projects and subprojects (unimplemented, will need a new data model)

 o add billing information (unimplemented)

 o new data modell, keep track of the invocations of each slot in the database.