title: Using Conditional Syntax (Overrides) in BitBake
body: <p>Reading <a href="https://rads.stackoverflow.com/amzn/click/com/178847046X" rel="nofollow noreferrer" rel="nofollow noreferrer">a book on Yocto</a>. Got to the following page, which says:</p>
  
  <blockquote>
    <p>BitBake provides a very easy-to-use way to write conditional metadata.
    It is done by a mechanism called overrides.</p>
    
    <p>The OVERRIDES variable contains values separated by colons (:), and
    each value is an item we want to satisfy conditions. So, if we have a
    variable that is conditional on arm, and arm is in OVERRIDES, then the
    version of the variable that is specific to arm is used rather than
    the non-conditional version, as shown:</p>
  
  <pre><code>OVERRIDES = "architecture:os:machine"
  TEST = "defaultvalue"
  TEST_os = "osspecificvalue"
  TEST_other = "othercondvalue"
  </code></pre>
    
    <p>In this example, <code>TEST</code> will be <code>osspecificvalue</code> due to the condition
    of os being in <code>OVERRIDES</code>.</p>
  </blockquote>
  
  <p>I'm unclear from this explanation how did <code>TEST</code> become equal to <code>osspecificvalue</code>. Would someone be able to explain it?</p>