krupicka
Double Eagle Member
How wide is a line? In property law, the line itself has zero width. You are either one side of the line or another. Following this logic, the TD would have to specify which side of the {wall, fence, string, etc} is the boundary.
By the clarification you gave earlier, the inbounds side of the physical element is the boundary.
In pretty much every sport a line has some width. Each sport defines if the line is in bounds or out of bounds.
In disc golf, the OB line itself is OB.