[Gmsh] 0 element number

[Wayne Christopher]

I have a msh that was written out by gmsh (a recent 2.5.1 build) that 
has this element definition:

18362 2 2 0 15 13962 0 17476

I don't understand the 0 node number - the nodes in the file start at 
1.  Does this indicate a degenerate element or something like that?

     Wayne