In generating client invoices with the Billing feature, it would be a significant improvement if we users could add a editable column field to individual line items. This column field could be editable either 1) when selecting line items or 2) when they appear on the invoice view. Clients require things like field ticket number, service performed, client site that relates to each line item. Currently users can override hours, rates and add comments, but the comments don't appear on the invoice and serve little client purpose. Invoice generation in professional services can have a large potential for late changes to line items or providing client extra details, and so I believe you would have much great adoption of the Billing feature in Replicon if you provided a little more customization to it.