What is a sequence of numbers or letters that opens a lock called?

A Senate report said which ruler's government, deposed in 2003, stole billions from the UN's Oil-for-Food program? A senator during most of the 1790s, which man came out of the election of 1800 as vice president? What did the senior citizens' group AARP originally stand for? Which U.S. president died in Buffalo in September 1901, eight days after being shot by an assassin? A series of 1995 raids in California found dozens of Thai immigrants working in which kind of substandard garment facto… A series of comebacks highlights which man's life, including a final term as British prime minister at nearly 77 in 195… A series of novels including "Iron Knight, Silver Vase" and "Precious Sword, Golden Hairpin" includes which one filmed… A series of travel guides gives its title to which 1985 Anne Tyler novel?