Dimensions "Support: vs other

I am not clear how to interpret the dimensions. I see "Support 13 x 394mm" in the data when I am expecting to see "22.5 x 15.5". Reference: A01065

<img width="629" alt="tate" src="https://user-images.githubusercontent.com/14003618/27016775-0da91cd6-4ef1-11e7-8408-01aaa2688762.png">
