vAvg calculates centroid for each individual marker based on the average position of selected verticies.

Steps

1. Select the marker object.
2. Click vAvg on the XROMM tool shelf.
3. Right click-hold and select vertex from the marking menu.
4. Drag your mouse over a single marker (selected vertices should become yellow).
5. In the Marker Name box, enter a name for the marker.
6. Press the Calculate Centroid button and a locator will be created.
7. Repeat steps 3 - 8 for each marker.