Delta setting for generic datasource

Hi to all,

I am little confused with upper limit and lower limit in delta setting for generic datasource.

Example: Delta field is calday, and upper lower limit is set to 1. So it mean that it new delta comes with 1 day old record.

But then what is use of upper limit here.Can any one explain me when to use upper limit scenario.

Regards

Pavneet Rana