You can choose to show an association name direction arrow for each association name. The association name direction arrow is a small, filled-in triangle that indicates the direction in which to read the name of an association (for example, "Customer" makes "Reservation", not "Reservation" makes "Customer".
The name-direction arrow has no semantic significance, it is purely descriptive. The original direction of the association name direction arrow depends on how you draw the association line: which class you start on and which class you end on.
Changing the direction
To change the direction of the association name direction arrow, open the the definition dialog of an association. On the Definitions tab, click Flip name direction.