Has automated the population of the Line Item Number field on the Invoice Line entity in PSA.  From what I can gather the Line Item Number field is also on the Quote Line and Contract Line and mapped between the 3 entities via their relationships.  If the Contract begun as a Quote then the Line Item Number is populated onto the Contract Lines and Invoice Lines. Otherwise not. 

Ideally what I would like to do is auto-generate sequential Line Item Number values for each line on an invoice (similar to how PSA does it for a Quote), regardless if the process started from a Quote or not.  Has anyone done this before?