In base component when user change the serial number we need to set date time in Extra attribute filed

HI Team,

In ibase component when user change the serial number we need to set date time in Extra attribute filed..if we click edit ,User change serial number after save we need to set date time in  Extra Attribute 4 field .

Component - PRDGENSET

In this component there is no attributes,so where we need to implement and how to implement please help.

Thanks

kalpana