The receipt for the vote should not indicate the names or parties of the candidate(s) voted for, though it could, for example, say the voter did cast a vote for races a, b, & c, but not d. Otherwise, people could be pressured (Boss: "Bring me your voting receipt before I determine your bonus") or paid off (dim to bum being loaded on bus to polling place: "Bring me your receipt showing you voted for the dims before I give you your pack of cigarettes") for their votes.