All supported DevTest releases.
For example, you have 4 Request data arguments and you have 6 columns in Excel file. The request matching is going to happen on all the Request data arguments and the corresponding 2 columns which were not mapped with Request data but these can be used in your VSI response.
Excel file can have as many columns as it can but all the Request Data Arguments in a transaction need to be mapped to the Excel data. For example, if a transaction has 5 Request Data Arguments then all the arguments need to be mapped to the Excel Data. Mapping 1/2/3/4 will return No Match.
Refer to these sections in the documentation of the DevTest release you are running:
Create Data-Driven Virtual Services --> Map Response to Data Set Columns
Read Rows from a Delimited Data File Data Set
Read Rows from Excel File Data Set
Create Your Own Set of Large Data Data Set