Model Geometry > Editing Model Geometry > Reverse Node Order for Selected Elements

Modify > Reverse Node Order for Selected Elements has the following effects on selected elements:

Members: The starting node becomes the ending node, so the local X axis points in the opposite direction.

Reverse member node order start

leads to

Reverse member node order end

Shells: If the node order was originally 1-2-3-4, the order will be revised to 2-1-4-3. Notice that this has the effect of reversing the direction of the local z (normal) axis, as well as reversing the direction of the local x axis.

Reverse shell node order start

leads to

Reverse shell node order end

(Wondering why it didn't result in 4-3-2-1? Because, while that would have the effect of reversing the direction of the local z (normal) axis, it would also introduce the possibility of changing the orientation of the local x axis, rather than guaranteeing that it was simply reversed.)