Some packages, like unrar, aren't build for arm?

[David Fokkema <dfokkema@ileos.nl>]

Hi group,

I noticed that unrar-nonfree isn't available for arm. Looking up the
developer's page and checking the buildd logs I noticed an 'n/a' next to
'arm'. How can I find out what the reason for this exclusion is? Is it
some binary code which only runs on i386??

Thanks,

David