I've been using Word on Mac for some decades now and have moved across to a PC which is so convoluted but have somewhat mastered it now. If you are looking for the invisible text boundary in Word 2013 you will find it if you click on to File in Top Menu then Options, which brings up another screen, then go to Advanced. Scroll down to you get to Show Document Content, where you should find a tick on ShowText boundaries. It is not like a normal page text boundary as it moves along with you when you type, which is annoying, but at least it is there for those that like to use it.