In first past the post bloc voting, each voter places n Xs on the ballot paper, where n is the number of candidates to be elected. The n candidiates with the highest number of votes are elected.
In preferential bloc voting, each voter places the numbers 1..n on the ballot paper. Candidates with the smallest tally of first preference votes are eliminated (and their votes transfered) until a candidate has more than half the vote. The system is re-started n times with the elected candidates removed and all votes returning to full value.
The bloc voting system is extremely undemocratic, allowing complete landslide majorities and small cohesive groups of voters to overpower larger groups which do not engage in tactical voting.
Bloc voting has its origins in common law [can someone confirm or deny this?]. It was used in the Australian Senate from 1901 to 1948 and is often used to elect the boards of directors of corporations.
wikipedia.org dumped 2003-03-17 with terodump