What is dual arch ?

Hi,
On the main website, when you open the download page : http://mageia.org/en/downloads/
There is a dual arch CD
What is it ?
Shouldn't we put some explanation and description of the CD / DVD to explain the differences ?
Pierre
On the main website, when you open the download page : http://mageia.org/en/downloads/
There is a dual arch CD
What is it ?
Shouldn't we put some explanation and description of the CD / DVD to explain the differences ?
Pierre