turtle  -- Command, one input.  Abbreviation: tur
     The input is the name of a turtle.  You can only control one turtle at
     a time, so using this command a second time releases the turtle previ-
     ously selected.  The names of floor turtles are numbers like 0 and  1.
     If  you are using a graphics display terminal (not just a text display
     trminal), you can control the display turtle by using the word display
     (or  the  abbreviation  dpy)  as the turtle name.  (As usual, the word
     must be preceded by a quotation mark.)  If you use a  graphics  primi-
     tive without selecting a turtle, Logo assumes that you want to use the
     display turtle.  But once you select a floor turtle, you must say tur-
     tle "display explicitly to switch to the display.

     The word off as input to the turtle command releases a  floor  turtle,
     if  you  have  one, or turns off the graphics display if you have been
     using the display turtle.  This also happens when you leave Logo.
