Words Gone Wrong: Proscribed, prescribed, or something

I feel some sympathy for the people who made this mistake:

Successful applicants will have until last mail October 14, 2011 to claim their rebate. Rebates not claimed by that date in the proscribed manner will be forfeited.

(Emphasis mine.)

Proscribed, not prescribed. For those unfamiliar with the word, here's a definition of "proscribe", courtesy of the OED:

proscribe: verb [with object]
    forbid, especially by law:
        strikes remained proscribed in the armed forces

Therefore, if you replace proscribed with a synonym, such as forbidden, the last sentence reads:

Rebates not claimed by that date in the forbidden manner will be forfeited.

Oops.

The word they're almost certainly looking for is prescribed. If we again substitute a synonym - say required - we get the much more sensible sentence:

Rebates not claimed by that date in the required manner will be forfeited.

As I said, it's an easy mistake to make. Don't be the sucker who makes it next.