I suspect the AEC island was probably done in WrpTool and then binarized to make it OPRW v3 format.
I have no idea how WrpTool works or if it supports saving out parts of islands, including objects.
You might want to ask over at
their forums, or read the large manual that comes with the program.
As for WrpEdit, it can save out parts of islands, but if I recall correctly it only saves the terrain and not the object information.
Its a long time since I tried this sort of thing. ;D ;D
Planck