There is a registered FITS keyword INHERIT
that controls whether an HDU inherits the keywords in the PDU. It is quite clear that they should if INHERIT=T, and should not if INHERIT=F
The BNL MEFs that Merlin and I have been looking at for monocam do not include an INHERIT keyword, but are clearly expected to inherit the PDU as each amp is in its own HDU bereft of any useful information such as exposure time.
What is the common expectation in the community when reading files like this? I don’t think that cfitsio or pyfits merges the headers (but I’m not sure they obey INHERIT either; we do). What should we do in afw – the current behaviour is causing problems?