What will be open for business: Parts of the government that provide what the White House budget office deems critical would still operate.
Critical services, broadly speaking, protect human life and property. Typically that has included air traffic control, national security, the handling of hazardous waste, food inspections, border protection, maintenance of the power grid and disaster assistance.
http://money.cnn.com/2013/09/19/news...html?hpt=hp_t2