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I would like to understand format of extended partition (EBR) meaning exact bit positions and locations of data blocks describing meta info about the following and (probably) the next partition.

Does anybody know the document that describes the format?

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up vote 3 down vote accepted

The description of an extended partition is contained in the first block. It consists of a standard partition table. The first entry describes the partition. The second entry if any describes the location of the next extended partition.

Wikipedia has a good description of the MBR which contains the layout of the partition table.

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To clarify that a bit, an extended partition looks like a whole disk with its own partition table and contains at most two partitions: a logical partition, and another extended partition nested inside it, which in turn may have another extended partition nested inside it, etc. – psusi Feb 13 '11 at 16:34
Thats what I have seen. Just no code in the MBR. Maximized partitions will start the data in the second sector. Otherwise the partitions starts on the second track. This is a hangover from the old Cylinder, Track, Sector addressing scheme. – BillThor Feb 13 '11 at 16:44

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