After you use a transparent command to establish the X and Y coordinates of a point location, you can specify the Z coordinate.
Specify an elevation using any of the following methods:
The default elevation, displayed at the prompt, is determined by the transparent command in use. If the current transparent command is ‘PN (point number), ‘PO (point object), or ‘PA (point name), the default elevation is taken from the specified point. In all other cases, the default elevation is the AutoCAD default elevation.
A transparent command can only be used within a running command.