Query regarding payroll status it 0003 & IGMOD

Hi Guys,

I want to ask some basic parts of payroll;

First,what is the exact use of payroll status it 0003 in payroll,whenever i am giving any date on run payroll upto checkbox in this it the message is coming "Run payroll up to must be within the inactive period",what does it actualy mean;can i give date on this box manually,What the Run payroll upto box served for?

Secondly,What the purpose igmod serves for for it.

Thanks

regards

Surajit