Interface SheetData

Sparse cell values — the same encoding IWorksheet.JSON.data uses (Scalar.JSON is already just the value+type pair; style/formula live in sibling fields there, none of which apply to a values-only cache).

<sheetData refreshError="1"> — Excel could not refresh this sheet's cache last time it tried.

Position in IExternalBook.getSheetNames this cache belongs to — the XML's sheetId, 0-based.