Half agree, I'm half correct.
REVOLVE used to be a solids-ONLY command.
I'm currently using AutoCAD 2006.
According to the HELP file:
"You can revolve closed polylines, polygons, circles, ellipses, closed splines, donuts, and regions."
The REVOLVE command in 2006 will not work with a simple line.
I get the *Unable to revolve the selected object.*
I just tried the same thing in AutoCAD 2009, 2010 and 2011 (yeah, multiple versions in the same office = oh joy) and you are correct, the *new* REVOLVE command will create a mesh / face from a line.
I don't know when this was changed but I'm guessing it was introduced with AutoCAD 2009.
Higgs: what version of AutoCAD are you using?
Wondering if there's more going on here than meets the eye, like is AutoCAD 2009 and later recognizing the line and invisibly *changing* the command to REVSURF?
In AutoCAD 2006, using REVSURF on a line and doing a LIST on the resulting entity gives:
Command: list
Select objects: 1 found
Select objects:
POLYLINE Layer: "0"
Space: Model space
Handle = 1508d
7x7 mesh
VERTEX Layer: "0"
Space: Model space
Handle = 1508e
Mesh
at point, X=20361.256 Y=18946.329 Z= 0.000
VERTEX Layer: "0"
Space: Model space
Handle = 1508f
Mesh
at point, X=20254.442 Y=18946.329 Z= 0.000
etc., etc., bunch of vertices and meshes, not a REVOLVEDSURFACE like James Cannon got.
I'm stumped, for now.
*EDIT - Properties box shows the REVSURF'ed line to be a Polygon Mesh.