Browser Extensible Data (BED)
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A BED file has 3 to 12 columns, the first three
3 columns are mandatory.

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Column NO.   Column Name       Description
============ ================= =========================================================
1            chromosome        name of chromosome
2            start position    start pos of the feature
3            end position      end pos of the feature
4            name              name of the feature
5            score             a numerical to represent the significance of the feature
6            strand            the strand information where the feature located
7            thick start
8            thick end
9            RGB
10           Block count
11           Block size
12           Block start
============ ================= =========================================================