Flutterby™! : I've had work reasons to look at

I've had work reasons to look at Flutterby.com's RSS feeds recently, and it's clear I need to revamp things, but I'm trying to figure out where to put the plain text, where to put the HTML encoded versions, and so forth.

I'm also using the Perl XML::RSS module, which may need to change.

Anyone got suggestions on a good one-pager about modern RSS in practice? I probably literally haven't mucked with this code in two decades.