Hi, Susan - If you're sending somebody a tune so they can listen to it, it's probably best to send it in MIDI format because it's a universal standard. Noteworthy Composer is very good at producing tunes in MIDI format.
If you want to send tunes with lyrics attached (which is want we prefer for submissions to the Digital Tradition), using Noteworthy Composer's own format is preferable. There is no universal standard for tunes with lyrics attached, but Noteworthy Composer's format is the most common format I've seen and it's the format we've agreed to use as the standard for Digital Tradition submissions.
-Joe Offer-