Add PO Item Number to line items

[fender21]

Love this API tool to generate invoices, so thank you very much! Often times I have to provide a Purchase Order number at the header and a PO Item Number on each invoice line item. I added a custom header element for Purchase Order, so that's no issue. I do not see a way to add PO Item Number on each invoice line item or see that line items support custom values? Can you let me know if custom values are available? If not, any other way to add in that attribute as a new column on the line item level?

[jaredk2g]

Currently invoice or line item-level custom fields are not supported. One workaround to this is to put your purchase order in the line item description which is a free-form text field.