[ 'customer_detail' => [ 'title' => 'Customer Details', 'subtitle' => 'Detailed information about the student or customer.', ], 'summary' => [ 'title' => 'Invoice Summary', 'subtitle' => 'Breakdown of total amounts for this invoice.', ], 'items' => [ 'title' => 'Invoice Items', 'subtitle' => 'List of products or services included in this invoice.', ], 'select_invoice_type' => 'Select Invoice Type', ], ];