Sheet Worksheet List
It seems likely there can be more than one worksheet in the file format, though there is always only one found (so we have 02 followed by a single Sheet Worksheet List Element instead of a XListE in actual documents). All cell references at other places always have an unknown byte containing 00 associated with them: this is probably meant to specify the worksheet number.
Data Description
B Always 02?
XListE A list of Sheet Worksheet List Elements
Sheet Worksheet List Elements
As there is only found one worksheet in this list, the first byte is always 00 in real documents; how it is actually used is just a guess.
Data Description
B Worksheet number?
Offset Offset of the Sheet Worksheet