PNE files were created by using the EDUCATIONAL Version of AC this file type stopped working with the release of AC10 if I remember correctly and the only way to open them is to reinstall the EDU version from that time and even then you will not be able to "save as" any format that can be read in any modern version of AC. You might be able to export the 2D layouts as DWG and the 3D as 3DS or OBJ but they will not be AC native objects.
Eduardo Rolón AIA NCARB
AC27 US/INT -> AC08Macbook Pro M1 Max 64GB ram, OS X 10.XX latest
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