It encourages these young workers to be as flexible as possible, to go wherever the jobs are, so they can maximize earnings during each two-year window.

- No. 6 Paul Casey can't mathematically be No. 1 because he doesn't have enough other success within the rolling two-year window.

Dr. English owed $600,000 in taxes when the city took over the building in 1988, and gave her a two-year window to pay.

"We really only have a two-year window in which to buy these properties or lose them forever," Mr. Levy said.

In 2001, the state Legislature opened a two-year window for DNA retesting in older cases.

"We think we're in an environment over the next two-year window where interest rates will go up," Mr. LaNeve said.

The Democrats have a two-year window in which to confront their internal schisms and to present a stronger face to the electorate in 2008.

Carlos Beltrán is one blueprint for a successful survival of the two-year window.

"Now, with a two-year window, we're expecting a lot of gifts."

Edwards figured he had a two-year window to take advantage of the vaunted but aging offense.