Nate Pease, is this something we could use the new butler features for?

the new Butler policy and yaml files? If so: yeah, give it a shot! (as is the way with changes & new things I suppose you'll run into issues. Let me know how it goes)

We are pondering something similar at DM-4559 too!

Methods such as bypass_deepMergedCoaddId and bypass_deepMergedCoaddId_bits need to be added to the mapper of the obs package in order to run some coadd/multiband processing. We are wondering why not adding some default implementations in CameraMapper.

i wasn't sure if it's better to wait until after DM-4180.

DM-4180 is scheduled for summer 2016; I wonder if you want to wait that long?

Much is changing in butler-land over the next few months, tho I can't say exactly what classes/methods (yet). If you're going to put new methods into CameraMapper that might be ok. It might be safer to add a common base class that you all can share
Either way please keep me in the loop about what changes you are making in butler and let's coordinate work as appropriate.

Thanks for the information Nate Pease!

For decamMapper I will do changes in the old way to move on. Those were just some thoughts to possibly make it easier for future new cameras. And sure will keep you in the loop!

I've made some minor comments on the PR. Mostly just asking for clarification.

As an aside, I agree with Paul that we should look at how to clean up our policy files. There are tons of dataset definitions and many are almost identical. We also aren't always consistent between obs packages.