_extra_where, what is this underscore mean?

[ask9]

Hi guys

 

As I'm learning the code of ION Auth.

 

I encountered this Crazy but cool Method below,

public function extra_where()
{
	$where =& func_get_args();

	$this->_extra_where = count($where) == 1 ? $where[0] : array($where[0] => $where[1]);
}

 

The only thing that made me baffled here is the underscore infront of extra_where,

here below,

$this->_extra_where 

 

 

I know I already known this before, but for some reason I forgot the purpose of this underscore.

Perhaps I have alzhemer's? XD

 

Anyone familiar?

 

 

[trq]

The underscore has no special meaning. Some people however (including myself) name private properties & methods starting with an underscore just to make them easier to see.