UC: Invoice creation: user menu link
UC: Invoice creation: school page button
UC: Invoice creation: link from the monthly report
UC: Invoice creation: last invoice number
UC: Invoice creation: invoice form, schools
UC: Invoice creation: month selection
UC: Invoice creation: year selection
UC: Invoice creation: invoice number selection
UC: Invoice creation: default invoice number
UC: Invoice creation: validating the invoice form
UC: Invoice creation: invoice URL
UC: Invoice creation: blank preview page
UC: Invoice creation: ajax call to get the invoice data
UC: Invoice creation: invoice data service
UC: Invoice creation: invoice data UI
UC: Invoice creation: basic form
UC: Invoice creation: styling
UC: Invoice creation: missing teacher name
UC: Invoice creation: date & period