In volleyball, what exactly is considered a foot fault when
a) serving?
b) attacking from the back court part (i.e. by a player from the back row)?
Three possible options come to mind:
* players are not allowed to even touch the line.
* players are allowed to touch the line but cannot cross it.
* players can cross the line, but only partially (i.e. with just a part of their
feet) - just as the case is at the central line with regular attacks.