The MIDI specification allows for sequence files to be stored in a consistent format, thus allowing those files generated by one sequencer to be used by another. For example, you could use a music composition program like Digital Orchestrator to generate a sequence, then import it into QuickScore Elite for editing and printing.
There are different types of MIDI files; the most common are type 0, where all information is contained in a single multi-channel track; and type 1, which puts each channel of MIDI data on its own track. Type 2 contains multiple patterns which are arranged as a song. QuickScore Elite imports all three types. However, it only imports the first pattern of a type 2 MIDI file . When music is imported from a type 0 file, the program will give you the option to put each channel on a separate track. QuickScore Elite exports type 0 and type 1 MIDI files.
There are many MIDI files available commercially and in the public domain on various internet sites.