It means the host needs a definite head count for the planned event, and needs it by the date specified on the invitation.

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Options are the right to buy or sell these investment assets at a set price before a specified date in the future.

BBC: Hedging - a rough guide

Support for the markets stemmed from the Federal Reserve saying it would undertake another round of quantitative easing with no specified ending date, the European Central Bank announcing intentions to buy debt of troubled European nations, and China approving new infrastructure projects.

FORBES: Average Base Metals Prices Expected To Fare Better In Coming Quarters; Gains Seen As 'Moderate'

If the case is successfully postponed, it will begin later than the currently specified mid-February trial date.

FORBES: The Four Options Left For AT&T's Troubled T-Mobile Acquisition

Apple release their staff from having to deliver products by a specified date, rather they can deliver when the product is ready.

FORBES: Where Was Apple's Hardware Release For March?

Also, in some cases, like Thailand, some of the new expenditure programs aimed at employment creation will end at a pre-specified date.

CNN: REFORM IS CRUCIAL

If the charges were not completely paid by the specified dates, then interest would be charged to the credit card account in an amount computed from the date of purchase.

FORBES: Avoiding Excess Credit Card Interest Should Not Be A Taxable Event