Hi,
Your directly creating data source in bw, so you won't use any ECC field.
You directly use bw info objects only.
if you use standard info objects then you may see related fields but not respective to flat file data source.
Based on your flat file field type and length, use available BW info objects and create data source.
later sue same info object at your target also.
RSDS - just shows the data sources which are in 7.x version.
Thanks