Tcl script that prompts the user to select nodes and displays their x, y and z coordinates

Tcl script that prompts the user to select nodes and displays their x, y and z coordinates:

#An example is a Tcl script that prompts the user to select nodes 
#and displays their x, y and z coordinates:
hm_markclear nodes 1
*createmarkpanel nodes 1
set nodes [hm_getmark nodes 1]
if { ! [ Null nodes ] } {
    foreach node $nodes {   
        set xVal [hm_getvalue nodes id=$node dataname=x]
        set yVal [hm_getvalue nodes id=$node dataname=y]
        set zVal [hm_getvalue nodes id=$node dataname=z]
        tk_messageBox -message "Node $node = $xVal $yVal $zVal"
    }
}