Indicates whether the data in Excel is laid out horizontally or vertically.
By default, the provider models vertically oriented spreadsheet data -- rows arranged vertically below a header row.
Set this to "Horizontal" if the rows are arranged left to right. The first column contains the column names and subsequent columns become rows.
The Header property is used in conjunction with the Orientation property. When Header is set to false and Orientation is set to Columns, column names are reported as R1, R2, R3, etc.
If you want to exclude any sheets from this rule you can set: Orientation=Horizontal, Sheet1=vertical (means orientation is set to horizontal for all sheets except Sheet1)