The CE technical documentation provides information on design, the construction and mode of a product and must include all the information required to demonstrate that the product complies with the applicable requirements of the European Union.

If you are a manufacturer, there are some rules that you must follow when placing a product on the market due to:

to prepare the technical file before placing the product on the market
ensure that market surveillance authorities have access to the technical documentation (on request) from the moment the product is placed on the market
to keep the technical file for 10 years from the date of placing the product on the market (unless expressly stated otherwise)

The technical documentation is necessary to prove that the product complies with the essential requirements and, therefore, to justify and support the EU declaration of conformity.