This value indicates whether or not a top label should be pushed onto the outgoing packet's label stack. The value of this variable MUST be set to true(1) if the outgoing interface does not support pop-and-go (and no label stack remains). For example, on ATM interface, or if the segment represents a tunnel origination. Note that it is considered an error in the case that mplsOutSegmentPushTopLabel is set to false, but the cross-connect entry which refers to this out-segment has a non-zero mplsLabelStackIndex. The LSR MUST ensure that this situation does not happen. This object cannot be modified if mplsOutSegmentRowStatus is active(1).