The Construction Products Regulation (CPR) is intended to ensure reliable information on construction products in relation to their performances. This is achieved by providing a “common technical language" offering uniform assessment methods of the performance of construction products.
Further information can be found at: http://ec.europa.eu/growth/sectors/construction/product-regulation/index_en.htm

The cable included under the CPR are those installed in permanent installation in construction ( buildings and other civil engineering works subject to regulation regarding safety in case of fire), while cables intended for mobile laying or which are not intended to be incorporated permanently in buildings (such as power supply, but also cables in power cabinets) are not subject to EU 305/11 (CPR) Regulations.
The DoP is a document drawn up for every product covered by the CPR by the manufacturer following regulatory guidelines.
Further information can be found at: http://ec.europa.eu/growth/sectors/construction/product-regulation/performance-declaration_en