I actually had it first with biennial, but thought but that would be the word for the event (like the italian Biennale) not the time interval, since it sounded

I actually had it first with biennial, but thought but that would be the word for the event (like the italian Biennale) not the time interval, since it sounded weird as an adjective. Oh the ambivalence; yet listing the years should make the intent obvious. Also if you use search, there are some more high profile SVG related posts that don't follow that made up pattern.