title: When should I use the dependency keyword <<use>> in UML diagram?
body: <p>Referring to <a href="https://www.uml-diagrams.org/dependency.html" rel="nofollow noreferrer">this source</a>, the definition of UML is</p>
  
  <blockquote>
    <p>Dependency is a directed relationship which is used to show that some UML element or a set of elements requires, needs or depends on other model elements for specification or implementation.</p>
  </blockquote>
  
  <p>But then, according to the textbook, <a href="https://martinfowler.com/books/uml.html" rel="nofollow noreferrer">UML Distilled</a>, in the section <em>Class Diagram: The Essentials</em> -> <em>Dependency</em>, the keyword <code>&lt;&lt;use&gt;&gt;</code> is described as</p>
  
  <blockquote>
    <p>The source requires the target for its implementation.</p>
  </blockquote>
  
  <p>Here, I can't see any difference between the general <strong>dependency</strong> line and the specific <strong><code>&lt;&lt;use&gt;&gt;</code></strong> keyword. Is there any case where the <code>&lt;&lt;use&gt;&gt;</code> is necessary or is it just redundant?</p>