if a coin is struck on the wrong planchet, is its face value worth which die was used or what the planchet was intended for? Example: If a cent is struck on a dime planchet, is its face value 1 cent or ten cents
I would think that face value would mean what the face of the coin is, a dime struck on a cent planchet would be a dime, a cent struck on a dime planchet would be a cent. Maybe I am taking the term face value too literally, but that is my take on it. OTOH a machine sorting would probably rely more on the planchet than the face on it.
By definition "face value" is the value stated on the face of the coin, so Chip isn't the only one taking the term literally. Remember, there is a zero degree of correlation between the "face value" and "market value" of coins, even though there are millions of coins worth exactly their face value, that's just a coincidence.