If primary headers will be allowed to have a name other than PRIMARY, they still need to be able to unambiguously report that they contain 'images' (really just non-table arrays though)
If primary headers will be allowed to have a name other than PRIMARY, they still need to be able to unambiguously report that they contain 'images' (really just non-table arrays though)

git-svn-id: 5305e2c1a78737cf7dd5f8f44e9bbbd00348fde7@1830 ed100bfc-0583-0410-97f2-c26b58777a21

spacetelescope/PyFITS,embray/PyFITS,embray/PyFITS,embray/PyFITS,embray/PyFITS,spacetelescope/PyFITS