How to create a procedure to get the project number and the sequence number in a purchase order

Dear All,

I am new to form personalization in Oracle apps. i would be grateful for the helping hands to clarify my doubt in the procedure creation. Let me narrate the steps that i am following for this personalization.

Requirement:
I need to create auto number value and project number separated by an oblique in purchase order creation, for which I’m capturing the project number value from the descriptive flex field. The format of the purchase order number will be as follows.

Eg.:

Project No. 600001, 600002, 600003 and so on…

P.O #:  Project No. / Sequence No.

P.O #: 600001 / 1

P.O #: 600001 / 2

P.O #: 600001 / 3