Erik Kostson
Ansys Employee

First of all, only if you have a split edge at the centre will the mesher guaranteed put nodes on that centre line - if there is no edge, then it can not be sure that the nodes will be on that centre line.
Having done the above, then one can select the edge, create a Named Selection - then highlight that named selection right mouse button click on it and choose create nodal named selection (that is shown below, created from Selection).

Another way is to use the worksheet in named selections to choose nodes at a certain location (you could define a local coordi. system there on the edge and use X=0, Y=0,.. to select them in the worksheet).

Hope this helps