Line objects ("line", "arrow", "spline", and "arc") can have one of the following attributes to specify which ends of the line contain arrowheads:
The first form (->) means that there is an arrowhead at the end. This is the default for "arrow". The second form (<-) means that there is an arrowhead at the beginning only. The third form means that there are arrowheads at both ends.
Note that "
arrow" and "
line ->" look identical to one another.
If there are multiple occurrences of these attributes on a single object, then the last one is the one that matters.