Subash
Please read the question which u sent across.
Generally reusable scripts/actions will using based on the requriment.
Eg: Login script (for any application this is must)
Inside the application there are different modules say saving and checking account.
For a bank customer will be login to the application to make a transaction. For any customer login is must. But the account number is different ie login id is different and he will doing different transactions.
In that case login script will be the reusable script. main script will saving Acc or checking account.
Regards
Madhu D