The round-pin power cords used on older Hewlett-Packard and Dolby equipment  uses a connector called the PH-163.  

The round-pin power cords using the PH-163 connector come in two versions. The difference between the two versions is that the hot and neutral are reversed. The ground is always in the same centre position.

Volex power cord model #17280 has standard polarity per UL 817 and CSA 895B.

Volex power cord model #17952 has  neutral and hot lines reversed.

There is only a risk for maintenance operations. There is no user risk under most applications.

In viewing the PH-163 connector from the end so that the centre earth contact is above the other two, then the neutral is on the left and the hot or line is on the right in the standard #17280 cord set.

In viewing the PH-163 connector from the end so that the centre earth contact is above the other two, then the neutral is on the  right and the hot or line is on the  left in the reversed #17952 cord set.

There is a discussion of this at a Department of Energy site.

Both items are listed at www.allied.com

Newark Electronics has a page showing both.