### Worksheet Object Each key that does not start with `!` maps to a cell (using `A-1` notation) `worksheet[address]` returns the cell object for the specified address. Special worksheet keys (accessible as `worksheet[key]`, each starting with `!`): - `ws['!ref']`: A-1 based range representing the worksheet range. Functions that work with sheets should use this parameter to determine the range. Cells that are assigned outside of the range are not processed. In particular, when writing a worksheet by hand, be sure to update the range. For a longer discussion, see Functions that handle worksheets should test for the presence of `!ref` field. If the `!ref` is omitted or is not a valid range, functions are free to treat the sheet as empty or attempt to guess the range. The standard utilities that ship with this library treat sheets as empty (for example, the CSV output is empty string). When reading a worksheet with the `sheetRows` property set, the ref parameter will use the restricted range. The original range is set at `ws['!fullref']` - `ws['!cols']`: array of column properties objects. Column widths are actually stored in files in a normalized manner, measured in terms of the "Maximum Digit Width" (the largest width of the rendered digits 0-9, in pixels). When parsed, the column objects store the pixel width in the `wpx` field, character width in the `wch` field, and the maximum digit width in the `MDW` field. - `ws['!merges']`: array of range objects corresponding to the merged cells in the worksheet. Plaintext utilities are unaware of merge cells. CSV export will write all cells in the merge range if they exist, so be sure that only the first cell (upper-left) in the range is set.