Open-source election counting
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BLT file format

OpenTally accepts ballot data in the BLT file format, as described by Hill, Wichmann & Woodall for their implementation of Meek STV. The BLT file format is also used by OpenSTV/OpaVote, Lundell's Droop and Otten's eSTV (where it is known as a DAT data transfer file).

The file format is as follows:

4 2
3 1 3 4 0
4 1 3 2 0
2 4 1=3 0
1 2 0
2 2=4=3 1 0
1 3 4 2 0

The first line (4 2) indicates that there are 4 candidates for 2 vacancies.

The second line (-2), which is optional, indicates that the 2nd candidate (Basil) has withdrawn. Multiple withdrawn candidates may be specified on this line, e.g. -2 -3 -4.

The third line (second, if there are no withdrawn candidates) begins the ballot data. 3 1 3 4 0 indicates that there were 3 ballots which voted, in order of preference, for the 1st candidate (Adam), then the 3rd candidate (Charlotte), then the 4th candidate (Donald). An = indicates that multiple candidates were ranked at the same preference. A 0 optionally indicates the end of the list of preferences.

The end of the list of ballots must be indicated with a single 0.

The next lines give the names of the candidates, up to the number of candidates specified on the first line (in this case, 4). Each candidate's name, unless a single word, must be surrounded by quotation marks.

The final line gives the name of the election, which, unless a single word, must be surrounded by quotation marks.

Newlines are optional, but if not provided, the 0 at the end of each ballot's preferences is mandatory.