SimplyMaya showing how to get started with creating a multi-pass render out of Maya for compositing in NUKE with Open EXR files. A great overview of creating multipass renders in Maya for creating ambient occlusion, diffuse, specular and shadow passes.
From the tutorial description: Render out multiple passes in maya as an OpenExr file then composite them in nuke. Tutorial aims to get you up and running with multipass rendering in Maya as quickly as possible. In this example we render out and comp an ambient occlusion pass a diffuse pass a specular pass and a shadow pass.