Peter Bunclark wrote:

x ? Why would a file be executable? In the tradition of the
omni-platform transportability of FITS files, it is unlikely that
a file would be really executable. If the executable was intended
to go onto a machine of the same architecture (and libc....) then
why use FITS?

An example of an executable file, however, would be a virus.

Another example would be a shell-script (requiring the execute bits),
bash/tcsh are pretty ubiquitous and portable. The extension is meant
to capture any foreign blob, this could include say a perl script used
as a pipeline recipe but stored in a foreign extension because the
archive
saving it is tuned to FITS files. Compiled binaries are allowed as
well,
but you'd be nuts to save them in this way.

-Mike