The french Series

Further Information

Before the adoption of the ISO standard system in 1967, France had its own paper size system. Some of these formats are still used today, and they are standardized by the AFNOR. Their names come from the watermarks that the papers were branded with when they were handcrafted, which is still the case for certain art papers. They also generally exist in double versions where the smallest measure is multiplied by two, or in quadruple versions where both measures have been doubled.

Source: Wikipedia