Hello, I am the inventor of Parallel Square Premusic, it is very much like ABC notation except enormously more robust and extensible.
[]ly__________Hap___birth___you!____Hap___birth___you!____Hap___birth___..._____Hap___birth___you!__ []ly___________-py___-day____________-py___-day____________-py___-day_______...__-py___-day_________ []ly____________________to____________________to____________________dear__________________to________ []sc --------d4d4||e4d4g4||F4------d4d4||e4d4a4||g4------d4d4||d5b4g4||F4--e4--c5c5||b4g4a4||g4------ []rh --------daad||dadada||daaaaaaadaad||dadada||daaaaaaadaad||dadada||daaadaaadaad||dadada||daaa---- []sc ----d4------||--d4d4||----a3--a3--||--a3a3||----d4--d4--||--d4d4||----g4--g4--||--d4d4||d4------ []sc ----b3------||--b3b3||----F3--F3--||--F3F3||----b3--b3--||--b3b3||----e3--e3--||--b3c4||b3------ []sc g2--g3------||g2g3g3||d2--d3--d3--||d2d3d3||g2--g3--g3--||g2g3g3||c2--c3--c3--||g2g3F3||g3g2---- []rh daaadaaa----||dadada||daaadaaadaaa||dadada||daaadaaadaaa||dadada||daaadaaadaad||dadada||dada----
You can read the documentation for my format at http://anticapit.al/ps/Parallel+Squares.html and http://anticapit.al/ps/Premusic.html. It requires very little explanation to read: only, first, interpret not individual characters but pairs or squares of characters, second, squares that are in the same column are parallel and refer to the same point in the music, and third, the first letters in each square line are the type square (here, lyrics, pitch in scientific pitch notation, and rhythm in the most intuitive notation conceivable...)
I look forward to the adoption of my format by many pieces of software, because it's better than all existing formats for the same information. There is no part of music that couldn't be adapted (likely in the most intuitive way) to a square character notation and appended to a square line in my format without breaking programs that only support the other types of square lines.
It's inevitable that this extension will eventually be updated to support my format. I'd love to speak to someone who could help me facilitate that.