You can export score files for the Csound synthesis system using File->Export->Export Csound score file.... Together with a suitable orchestra file (not supplied), this can be used to play the composition through Csound. Note that not all data in the Rosegarden composition necessarily can or will be saved in the Csound format.

You can use File->Export->Export Mup file... to save the contents of the current composition into a new Mup file. This can then be processed by the Mup music publication system, although it is likely that the file may need some tweaking to get really good quality output. Note that not all data in the Rosegarden composition necessarily can or will be saved in the Mup format.

The File->Export->Export MusicXML file... function saves the contents of the current composition into a new MusicXML file. This can then be used with any music software that supports the MusicXML format. Note that MusicXML support is experimental and has not been well tested. Not all data in the Rosegarden composition necessarily can or will be saved in the MusicXML format.

Rosegarden can import h2song files created by the Hydrogen drum machine. These are imported into a skeletal MIDI-style structure with one track per pattern. The audio samples they use are not imported. Use File->Import->Import Hydrogen file... to import a Hydrogen file.

Use the File->Import->Import Rosegarden 2.1 file... function to create a new composition from the contents of an existing X11 Rosegarden v2.1 (.rose) file.