public function getStreamPartStartOffset()
    {
        if ($this->parent) {
            return $this->streamPartStartPos - $this->parent->streamPartStartPos;
        }
        return $this->streamPartStartPos;
    }
public function getStreamPartStartOffset()
    {
        if ($this->parent) {
            return $this->streamPartStartPos - $this->parent->streamPartStartPos;
        }
        return $this->streamPartStartPos;
    }
public function getStreamPartStartOffset ( ) { if ( $ this -> parent ) { return $ this -> streamPartStartPos - $ this -> parent -> streamPartStartPos ; } return $ this -> streamPartStartPos ; }
Returns the offset for this part's stream within its parent stream.

@return int
Returns the offset for this part s stream within its parent stream .