This command is used in the ellipsoid mode of the potts/weld_jom application to define the maximum ellipsoid depth.
It is also used in the keyhole mode of the potts/weld_jom application to define the maximum depth of the shallow ellipsoid.
This command can only be used as part of the app_style potts/weld_jom application.
It must be a positive value.
Default: 1/4 * zhi