title: Makefile - $< for multiple rules
body: <p>According to the gnu make documentation <code>$&lt;</code> refers to the first prerequisite:</p>
  <blockquote>
  <p>$&lt;
  The name of the first prerequisite. If the target got its recipe from an implicit rule, this will be the first prerequisite added by the implicit rule (see Implicit Rules).</p>
  </blockquote>
  <p>But, if I have the following:</p>
  <pre><code>a: b
  a: c
      @echo first prerequisite is: $&lt;
  </code></pre>
  <p>This will print <code>first prerequisite is c</code>.  While this makes sense, (as it would raise to many sharp sticks if <code>b</code> was considered the first prerequisite), I'm not seeing any documentation to support this, I'm wondering if I can rely on this being consistent among other make systems (The POSIX standard also does not seem to expand on this)</p>