or 
depending on whether you want to expand or collapse the pane.To view a billing document:
If you want to expand or collapse the Billing Document Detail pane, click or depending on whether you want to expand or collapse the pane.
To view the tax codes on a billing document line item, click the Tax Value Total for that billing document line item. For information about calculating tax on billing document line items, see Calculating Tax on Billing Documents.
The Additional Fields tab shows the fields in the Billing Document Enhanced Billing Document Additional Fields field set. The fields in the Billing Document Line Item Enhanced Billing Document Additional Fields field set are shown as columns initially in the order specified in the field set. See Enhanced Billing Document Additional Fields.
Click the Additional Fields tab to view or edit the additional billing document fields.
The relationship of related object fields is indicated on the Additional Fields tab by '>'.
When editing a billing document, you cannot edit additional fields that are related object fields, formulas, or roll-up summaries. Additional fields that are related object fields, formulas, or roll-up summaries are not updated while editing billing documents. For instance, if the Additional Fields tab contains a field from a related object such as Account and you update the account on the enhanced Billing Document Detail page, the version of that field in the Additional Field tab is not updated while you are editing it.
To edit an additional field on a billing document line while editing a billing document or creating a new one, select the value you want to change or tab to it using your keyboard.