The Lock Fields check box allows you to lock certain fields in the Item Detailes section so that they can be placed on multiple line items without having to re-enter the values. The fields that are locked for entry are Project, Account, Organization, Need By Date, Vendor, POP Start & POP End Date, and Shipping Address.
Note:
Even if the Lock check box is selected, the information may be manually overridden at any time. If the Lock check box is not selected, then all of the fields are cleared after the line has been added.