You can specify the AUTO keyword in place of the data set type to indicate that the type of the imported data set is to be determined from the mainframe catalog. Using this feature means that you don't need to know what the data set type is in order to import and catalog it.
Example:
MFDAS IMPORT c:\mfi01.test.data.txt FROM AUTO mfi01.test.data /CATLOC=c:\proj\catalog.dat