Rule Definition
Even if making the code "cleaner" by copying predefined variables to variables with shorter names before working with them seems a good idea, actually it is not such a good idea because the results in is doubled memory consumption (when the variable is altered), and therefore, slow scripts. For example, if a user had inserted 512KB worth of characters into a text area field. This implementation would result in nearly 1MB of memory being used.

Remediation
Try to avoid copying predefined variables into other variables.

Violation Code Sample

<?php

$variable1 = strip_tags($_POST['variable']);
echo $variable1;

?>

Fixed Code Sample

<?php

echo strip_tags($_POST['variable']);

?>