What is the meaning of dashed arrow in UML class diagram?

Question

What is the meaning of the dashed arrow in a UML class diagram in general?

As an example: What is the meaning of the dashed arrow in this image (from client to ConcreteCommand):

Article: Command pattern

Answer 1

Between Client and ConcreteCommand::
It means dependency.
Dependency: The definition or implementation of the dependent classifier might change if the classifier at the arrowhead end is changed.

Between ConcreteCommand and Command means Realization::
Realization: The class implements the operations and attributes defined by the interface. The interface is at the arrow end of the connector.
(Use the Inheritance tool to create a realization between a class and an interface.)

Answer 2

The dashed arrow (from client to ConcreteCommand) means that there is an (unidirectional) association between instances of these classes. An instance of client is using an instance of ConcreteCommand but lifecycle of ConcreteCommand (creation and destruction) are not depending of Client instance. The direction of the arrow means that Client instance uses ConcreteCommand instance but not vice versa