! It doesn’t support xls file.
A dataset may contain one or more of your data files. But all data files within one dataset must be of the same data structure, i.e. the number of variables and their properties must be identical in each file.
The structure of the data (e.g. variable properties) and whether the data values fit to the specified structure (e.g. data type, value range) is evaluated.
An example showing the failed validation case: