This is most appropriate as a popup topic when it comes to Invoice Verify.
Line item headers appear on the invoice image in the Invoice Verify module, at the top of the line item table. The header names are the field names. Line item headers can assist you seeing what type of line item value you are verifying and where the value is located on the invoice.
For more information, see Adjusting the display in Invoice modules or Line items in an invoice solution: Overview.