table model: Width of colgroup defined by col elements

In step 9.1 of the table model processing algorithm, first case under

"Column groups. Process the current element according to the appropriate 
one of the following two cases:
If the current element has any col element children"

Step 9.1.7 sets the final width of the colgroup is given as 
x_max-x_start-1. I think this should be x_max-x_start+1.

Rationale:

Define the initial value of x_max to be x_max_0. According to step 9.1.1 
x_start is x_max_0 + 1

In step 9.1.4 x_max is increased by the current col's span and this step 
is run once per col child of the colgroup, so if there is a total width 
w of columns in this colgroup, x_max -> x_max_0 + w

So at step 9.1.7 we have:
x_start = x_max_0 + 1
x_max = x_max_0 + w => x_max_0 = x_max - w
x_start = x_max - w + 1
w = x_max - x_start + 1