when we point a unicode flatfile(DT_WSTR),external columns remain DT_WSTR, but output columns automatically turn to DT_STR, there is no need to use a DataConversion to convert from DT_WSTR to DT_STR
whereas
for excel source(DT_WSTR) external columns will not be converted to DT_STR output columns automatically
we need to use a DataConversion Transformation to Convert DT_WSTR to DT_STR
any specific reasons?