Syntax: !dr [arg]This will delete currently displayed rulers, as generated by the Rulers command in the View Menu. If no arg is given, the most recently generated ruler is deleted. The arg can be an integer, or `a'. if `a' is given, all rulers for the current cell are deleted. If a number is given, that ruler, counting backward from the most recently generated, will be deleted, i.e., 0 erases the most recent ruler, 1 erases the one before that, etc.