This tells Smarty how to handle PHP code embedded in the templates. There are four possible settings, default being SMARTY_PHP_PASSTHRU. Note that this does NOT affect php code within {php}{/php} tags in the template. SMARTY_PHP_PASSTHRU - Smarty echos tags as-is. SMARTY_PHP_QUOTE - Smarty quotes the tags as html entities. SMARTY_PHP_REMOVE - Smarty removes the tags from the templates. SMARTY_PHP_ALLOW - Smarty will execute the tags as PHP code. Embedding PHP code into templates is highly discouraged. Use custom functions or modifiers instead.