Changes

Headers are not mandatory, but if present they should be contained in just one row (the first one) and not be in mergedcells.

'''Multiple Data Tables''' Only one table per spreadsheet can be imported. If the data in two different tables can not be joined, they must be imported as two separated data sources. [[File:headers_rightmultipletables_wrong.png|link=]] [[File:multipletables_right.png|link=]]   '''Merged Cells''' Data should not contain merged cells for repeated values. All cells must be unmerged and values must be repeated for each cell. [[File:mergedcells_wrong.png|link=]] [[File:mergedcells_right.png|link=]]