By the way, I think ABC is a great way to exchange melodies.

If you're limited to text here, there really isn't a better system I can think of at this time.

It's very easy to read.

There are existing open source databases of tens of thousands of tunes that are readily searchable. I have over 65,000 traditional Irish tunes available in my tool.

You can easily generate notation or play it with many tools, including mine.

Using tools like mine you can easily transcode it to MusicXML or MIDI or transcode MusicXML or MIDI back to ABC.

It's able to represent anything from simple one-line melodies to full orchestral scores.

You can easily generate tablature from it for many instruments

It uses a very limited set of characters and symbols, so compresses well for generation of share links that actually contain the tunes, as I create for my interactive PDF tune books.

Those are just a few reasons I find ABC to be a very concise way to share tunes.