Some functions were given new, optional, parameters in PHP 5.2.x:
PHP Core:
double_encode in PHP 5.2.3.
    
   double_encode in PHP 5.2.3.
    
   strict
    
   httponly
    
   httponly
    
   httponly
    
   real_usage
    
   zend_extensions in PHP 5.2.4
    
   curl:
msgs_in_queue
    
   imap:
n_retries
    
   n_retries
    
   offset
    
    
      The offset parameter was put in the position
      the encoding parameter used to be.
      Backward compatibility has been
      provided by allowing encoding to be specified
      as the third parameter.  Using this backward compatibility mode is
      not recommended because it will be removed in a future release of PHP.
     
ming:
skip in PHP 5.2.1
    
   signature_algo
    
   connection
    
   connection
    
   is_prefix
    
   is_prefix
    
   is_prefix
    
   is_prefix
    
   is_prefix
    
   spl:
use_keys in PHP 5.2.1
    
   encoding
     and options
    
   encoding
     and options
    
   content became optional in PHP 5.2.3
    
   content became optional in PHP 5.2.3