Hello world!
I'm talking about moving the legs of bipeds in Alice3.
I have thor again.
While the arms are mirror images of each other 
and use opposite commands 
because they are on opposite sides of the body
and thus have a different orientation,
Legs both descend down from the body
but are mirror images of each other from left to right.

I've selected thors right hip
and I'm going to turn it backward 0.25.
And run that, and even though it says backward,
the leg is out front of him
because of the orientation.
I'm going to copy this to the clipboard
and drag that in there,
and change it to the left hip.
and run that and both legs stick out to the front.

So we use the same command.
I'm going to right click and disable both of these.
I'm going to use the roll command and roll to the left.
The right hip right roll to the left
You  can see he kind of turns his foot in
and if I turn roll to the right he turns his foot out.
I'm going to disable that also and copy to the clipboard.
And enable that.
and the right hip, I'm going to turn to the left and run that.
Well, humans can't do that!
So let's make that to the right
and he raises his leg off to the side.

Let's copy that to the clipboard and change it to the left hip.
And run it. I don't think humans can do that either!
But here's the thing: if we are moving forward and backward
the commands will be the same for the left and right part of the leg.
But if we are turning them to the right or the left out to the side
they're going to be the opposite of each other.
You probably need to experiment with that to get the hang of it.