Hi all, There's been quite a bit of discussion on yt-dev about changing the internal convention in yt of using "na" for numpy (which originally stood for "numarray") to "np", which is the commonly used shorthand. We'll keep around "na" in the yt.mods namespace, which means your scripts should *not* need any adjustment. But, if you have made a number of substantial changes to the internals of yt in your version, any updates after this change is made may pose problems and may need to be hand-modified. If you'd like to contribute to the discussion (we're waiting until next week to make the switch) please do so on yt-dev or here. This change, which touches many many files, was not decided on lightly and we're trying to ensure that the transition is smooth without any external effects. Here's the thread: http://lists.spacepope.org/pipermail/yt-dev-spacepope.org/2012-August/002353... (Note that tomorrow starts a new archive month, so you might need to switch the URL for any new messages after today.) Again, this should not pose any issues for you unless you have modified yt internals. If you have done so and would like help updating, please reply to this message or contact yt-dev. Best, Matt