node_cylinder has helpful and correct parameter names 'top_radius' and 'bottom_radius'
node_tube has 'radius' and 'radius2' for the same. This is inconsistent not only with node_cylinder but with OpenSCAD which uses radius2 for the top, not the bottom.
By the way, in the absence of any documentation I don't know why tubes have both an inobject and a holeobject. If holemargin is positive the hole and the holeobject are bigger than the inobject. Why is this? Is it so you can make a tube and an object that fits inside it with a loose fit?
Subject: node_tube has wrong parameter names 
Tue 14 Feb - 19:15