Architecting and designing
  
Arrowhead colors
Arrowheads can be white (or empty), hatched, or black.
When the arrowhead is white, the line is not attached at either end.
When the arrowhead is hatched, the line is attached at one end.
When the arrowhead color is black, the line is attached at both ends to another symbol.
The junction point of a line and the symbol to which it is attached looks like a cross when the line is selected.