While gritting my teeth and reading over an irs letter outlining why they are owed $345 from a couple years ago I came across this line.
4. Complete and return the installment Agreement Repuest (enclosed envelope --page 3.
This one is from CP2000 (Rev. 11/2004)
Meaning that it's a form letter sent out to anyone they think owes them taxes. Spell checker folks, it's your best friend. Especially if you are in a professional field. Especially if millions of people are likely to read it. No wonder so many people think the irs is full of idiots.