Architecting and designing : UML 2.0 Lite : UML models : UML Deployment diagram : Dependency
  
Dependency
A dependency indicates that one model element (source) depends on another model element (target), such that a change to the target element may require a change to the source element in the dependency.
In a deployment diagram, you can use the dependency relationship to show the capability of a node type to support a component type. You may also use the relationship to show the dependency between component types.
See also
UML Deployment diagram