I'm trying to export some DI mattes in EXR format, and need to be able to export layered EXRs. In cc2014 this was fairly simple if you had Fnord's PRO EXR tools. You could easily use the "File>create Pro EXR layer comps" function to create your layered comp with all the correct naming conventions and then export it using the Pro Exr Layers Sequence option. It would pickup all the naming conventions and pass them on, it was very handy.
With cc2015 this is no longer the case. The create Pro EXR layers comp function still exists, but Pro Exr Layers Sequence is no longer a format option. Open EXR is an option, but that doesn't pass on the layers at all. I can't seem to find any documentation on this either through Adobe or with Fnord.
As Fnord released Pro EXR free recently and cc2015 handles EXRs so smoothly now I assumed that there was a new simple way to write out layered EXRs. That's why I'm here though - I can't find mention of it anywhere. There is something cryptic in the PRO EXR manual
"If you are using After Effects CC 2014 and earlier, you also have the option to choose “ProEXR Layers Sequence” as a format in AE’s output module, and this is in fact the preferred method."
Suggesting, I think, that cc2015 *does not* have this same option. It does not go on to address how you're supposed to export layered EXRs after 2014.