I think once-in-one-hundred-year is a definition for weather events used in building standards (sorry to be vague and possibly misleading - if my resident archi

I think once-in-one-hundred-year is a definition for weather events used in building standards (sorry to be vague and possibly misleading - if my resident architect/partner was here, I could be more specific). I've certainly heard of constructions like levies etc "build to withstand once-in-a-hundred-year storms". I wonder if these standards are being revised by appropriate international bodies?