Merged Cells

<mergeCells>
  <mergeCell ref="D13:H14"/>
</mergeCells>

In the example, cells D13:H14 have been merged into a single, larger cell. Note that the cell table itself doesn't reflect this merge, but it does reflect the data content and formatting. Specifically, the top-left cell in a merged collection of cells contains the value, and all the cells reflect the various border formatting.