There is an agreement between CEN and ISO saying that they shall not work on the same Work Items. New work can only be started in CEN if it is not already on the ISO program and vice versa.
CEN-Technical Committees are encouraged to seek contact with related ISO-Technical Committees to agree on possible parallel voting. This means that the European standard (EN) may become a combined CEN-ISO standard (ISO-EN) if accepted by ISO.
Existing ENs will by preference be maintained by related ISO-Technical Committees. Only when related ISO-Technical Committees are not interested or not giving it enough priority, will the CEN-TC continue the normal 5 years maintenance schedule or faster if needed.
Author: Dick van DIJK (TNO)