I want to add the Line Sequence Number to the Purchase Order display in UI. Doesn't appear as an option on the Form Customization/Sublist. Tried creating a Custom Line Field, byt {linesequencenumber} doesn't get recognizd as a valid field in the Formula field. Any native way to display line numbering in the UI and then printing on a standard form layout (not Advanced PDF)

Custom line field > store value = unchecked > validation and defaulting > default value = {line} > formula = checked