title: What does "old code" for keyword abstract mean?
body: <p>I am new to php and learning OOP in php. One thing that i have found on the below reference link that <strong>Old code that has no user-defined classes or functions named 'abstract' should run without modifications.</strong>. Can anyone tell what does it mean ? Does it mean that in old version keyword <strong>abstract</strong> is not supported in old php or may be i am wrong ?</p>
  
  <p>Reference Link: <a href="http://php.net/manual/en/language.oop5.abstract.php" rel="nofollow noreferrer">http://php.net/manual/en/language.oop5.abstract.php</a></p>