How do you read date stamp?

I have a Birkin bag with a stamp which is an A inside of a circle. I read a post saying A-Z in a circle would be 1971-1996 respectively. That would mean my bag was made in 1971 but it is a Birkin and they weren't even being made until 1984. I'm confused!
 
HermesBirkinBag012.jpg
 
Kim what you posted above is correct. The Birkin was first made in 1984. Your bag is dated to 1971. So not only is the datestamp incorrect but the hardware is never screwed on like that.