Yeah, that was it.
And as for this book I've been working on, I had intended to just give it away for free, and while I was only going to bother to put it together in EPUB format, I'm sure there will no doubt be people out there who will want to convert it to MOBI format, too. So sure, I could do these images up in SVG because I do agree that it's "better" (for devices that support it), but the difference in
visible quality of the images that you see is virtually negligible -- never mind the TON of extra work it would be to create an SVG version of this music from scratch, in order to bring the file size down -- so why on earth wouldn't I just go with PNG instead? Seriously, it looks pretty much just as good, and it's all-around compatible. I really don't understand the argument in favour of doing a TON of work just to make something that looks
negligibly better, and is less compatible. :/