Export Reference : Select any part of the reference character, click it to output reference info to Maya temp folder.

Tips: Right mouse button clicking on this button and select "View reference path.." :  The window that pops up will show the actual reference path in "\" style . U can copy this and paste it in the "pick file to reference " window in future.

Import Reference :Reuse the information output before. Will reference the same character in same manner.

Remove Reference : Remove the selected reference completely including the namespace that it takes. Notice it cant remove the double referenced objects.

Replace nameSpace :Replace the selected reference node 's namespace with a new one. If the new namespace has been taken already, it will first delete the objects that occupying the namespace  and pre-empty the namespace.

Tips: This could be handy when u have a situation that character's namespace is followed by number. Such as u want to reference a character like "Tom:..." but it ends up with "Tom1:.." or "Tom2:..." or else, this is because the namespace "Tom" is already used by some nodes in your scenes that u don't know. Use the tool to correct it by force.