Is there a way to add a column groupings? For example:
Unit 1 | Unit 2 | Pre Mid Post | Pre Mid Post | --- --- ---- | --- --- ---- | 2 4 5 | 3 4 4 | 1 2 4 | 3 4 5 |
Basically, I need a header row for Unit that has three subcolumns in the Unit group; Pre, Mid, and Post.
This concept can also be seen in following pictures: