Automatic Creation of Proj def & Network Activity while cration sales order

Dear All,

I want to know how system creates project order after creating sales order.

Where is the link.

I have used std. sap data (IDEAS)

Sales Order Type PS1

Sales Area 1000/10/00

Sold 2 party 1600

Material E-1001

Company Code 1100.

I have created sales order and then releasing proj in t-code CJ2B.

And confirming the activity.

I would like to know how system automatically creates Proj def. and Network.

Regards,

Sainath