O'ring measurements

I going to order some orings from the O'ring Store but I'm a little confused on FX's part's list. On the PDF file from FX, they give all their oring measurements like this: 2,5x1,5. On the O'ring Store they give their oring measurements as 1.5mm x 2.5mm and their measurements are CS x ID. Is FX's measurements ID x CS? I want to make sure before I order orings. I don't want to be stuck with the wrong sizes.
 
Forget the comma and look at it as a period. I don’t know why FX uses a comma, but it would be, using your example, 2.5 as the inside dimension/diameter, and the 1.5 is the section thickness.

dont swap them, order them exactly as FX notes them in the parts diagram. 1st number is inside diameter and 2nd is the thickness. 

Thats why I like to use oringandmore.com, as their o rings are also called out the same way.