The invoice is a document that reflects the purchase of a course or service . This is issued by the entity that sold the aforementioned. In the case of Nivelat, it will issue an invoice when the end date of a SENCE course has been completed.
When a company registers a course through SENCE or in an OTIC. This organization sends to the OTEC (Nivelat), who will teach the course, a Purchase Order with all the specifications for the SENCE course registration.