Parents began lining up after midnight Monday to win one of the 20 open spots in the highly regarded pre-kindergarten program at Mary Lin Elementary in Atlanta’s Candler Park. Registration for the school begins Thursday. All 4-year-olds are eligible for the free, lottery-funded pre-kindergarten program, regardless of their parents’ income. The state lets local program directors decide how to handle registration provided the process is open, fair and non-discriminatory. Many schools and centers hold lotteries. Others, such as Atlanta Public Schools, award seats on a first-come, first-served basis. The camp-out at Mary Lin Elementary has become an annual tradition. The quiet street resembled a camping ground with lines of RVs, grills, mess tents and picnic chairs. Some parents sat outside typing on laptop computers and returning work phone calls. Many parents used vacation and sick days to take time off from work to wait. Still, the parents set some rules. They agreed to 15 -minute bathroom breaks at reasonable intervals. Break the rule and you forfeit your spot. They also exchanged cell phone numbers. If called you must appear within 10 minuts or lose their place in line.