Keywords in "fix wall/piston command"

Hi All,

I got a question regarding the meaning of the “args” of keywords “pos” and “vel” in “fix wall/piston command?” The doc says that

*"pos* args = z
    z = z coordinate at which the piston begins (distance units)
  *vel* args = vz
    vz = final velocity of the piston (velocity units)"

which seems: pos needs only one argument z, and vel needs only one argument vz (the z component of the piston).

But in the Example part of the doc:  fix walls all wall/piston zlo pos 1.0 0.0 0.0 vel 0.0 0.0 10.0 units box

There are three args for each keyword, what is the meaning of those three values?

Thank you very much,

That is an error with the doc page. This command requires x, y, and z coordinates for the pos keyword and x, y, and z velocities for the vel keyword. Note the wall can only move in the +z direction, so x and y velocities have no effect at all. The same for x and y for pos keyword - they have no effect. There may be a need to change the source code to match the doc page, since the doc page makes more sense to me.