pending: If the payment of the invoice is not received, then the invoice status is shown as "pending". It will be initial status when the invoice is created.
paid: When invoice is received full amount, invoice status will be shown as "paid".
under paid: If the payment of the invoice has been paid in part, the invoice status is shown as "under paid".
over paid: f the payment of the invoice is greater than amount value, the status of the invoice is shown as "overpaid".
expired: if the payment of the invoice does not complete before the expiry time, the status of the invoice is shown as "expired".
cancelled: if customer cancels the invoice, the status of the invoice is shown as "cancelled".