public function getRef()
    {
        if (is_null($this->ref)) {
            $tags = $this->tags;
            sort($tags);
            $this->ref = md5(implode('-', $tags));
        }
        return $this->ref;
    }
public function getRef()
    {
        if (is_null($this->ref)) {
            $tags = $this->tags;
            sort($tags);
            $this->ref = md5(implode('-', $tags));
        }
        return $this->ref;
    }
public function getRef ( ) { if ( is_null ( $ this -> ref ) ) { $ tags = $ this -> tags ; sort ( $ tags ) ; $ this -> ref = md5 ( implode ( '-' , $ tags ) ) ; } return $ this -> ref ; }
Gets a unique reference to name the TimePoint
@return string
Gets a unique reference to name the TimePoint