It seems to me that we could use a good bit of information (someday perhaps published as a table) as to how the clothing sizes of different brands match up. (what did you think I was asking?)
For example, I'm most familiar with the sizes quoted by Performance Bikes for their own brand of clothing. I buy from them because I understand the size information. Other brands, especially those made in Italy are considerably smaller for the same posted size.
At least one of the sites I have delt with in the past has a comparison chart for different brands of shoe.............ie brand a's 46 is a 12 US, is a brand b 47......etc. What a great find. (If I ever find it again, I'll publish it here.)
Here's the starting point. Performance bike has accurate information for sizes because they post the real waist or chest size along with the L, XL, XXL.