Hundreds of medical marijuana dispensaries face a deadline Monday, but questions remain about how exactly that deadline will be enforced.

More than 400 dispensaries are under orders to close in accordance with the city's news medical marijuana ordinance. Eventually, the city hopes to whittle the number of pot shops down to 70  and to limit outlets to industrial areas.

Some estimates peg the number of medical marijuana dispensaries  operating last summer in Los Angeles at 1,000. City officials said hundreds were not registered.

Dispensaries that opened before the city declared a moratorium on Nov.  13, 2007, will be allowed to stay open but, within six months, they will have  to comply with the ordinance, which has a strict zoning component.