A broker`s notification from a client who wants to exercise a right to buy or sell (depending on the type of contract) the underlying security of the option contract.
Cap on the number of option contracts of any one class of contract. that can be exercised within a f
A formal notification that the holder of a call/put option wishes to buy/sell the underlying security at the exercise price.
The formal notification that the holder of a call (or put) option wishes to buy (or sell) the underlying security at the exercise price. 
A formal notice to the writer of an option from a clearing house that an option has been exercised... <a target=_blank href='http://www.finance-glossary.com/terms/exercise-notice.htm?id=522&ginPtrCode=00000&PopupMode=false' title='Read full definition of exercise notice'>more</a>