San Francisco is moving toward ID cards for undocumented immigrants. Mayor Gavin Newsom signed a bill requiring the city to issue ID cards to people who can't or won't apply for a driver's license. The ID card will not be a substitute for a driver's license. It's not a work visa or a Social Security number. But it will qualify undocumented immigrants for health services provided by the city as well as public library privileges and resident discounts at city museums.