As this is an important international standard, it is useful to add tags for EN 301 549. I think we can do that very similar to how we do WCAG tags. Each rule that maps to EN 301 549 gets an EN.301549 tag, and a second tag referencing the section. These are all part of section 9, so for wcag111 that would be EN.9.1.1.1

One open question here is what to do with WCAG 2.2. That will likely be part of of EN before the end of the year. But since there's a transition period before it becomes required, I'm not sure whether we should tag that rule as soon as it's in EN, or if we should wait with that.