[Gmsh] Third and fourth order tetrahedra?

[Rui Maciel]

The manual's "MSH ASCII file format" refers to 20-node third order tetrahedra 
and a 30-node fourth order tetrahedra.  Yet, I haven't figured out how to use 
Gmsh to generate meshes which included those elements nor are those elements 
covered in the manual's node ordering section.

So, is it possible to generate meshes of these tetrahedra with Gmsh?  If so, 
could anyone explain how it's done and what's the node ordering for these 
elements?


Thanks in advance,
Rui Maciel