Attempting download from Enhydra website of the .zip file. MPE/iX 6.5
responds with error:
$unzip enhydra3.1.zip
Archive:  enhydra3.1.zip
  End-of-central-directory signature not found.  Either this file is not
  a zipfile, or it constitutes one disk of a multi-part archive.  In the
  latter case the central directory and zipfile comment will be found on
  the last disk(s) of this archive.
note:  enhydra3.1.zip may be a plain executable, not an archive
unzip:  can't find zipfile directory in one of enhydra3.1.zip or
        enhydra3.1.zip.zip, and can't find enhydra3.1.zip.ZIP, period.
So, I'm a rookie.  Where'd I go wrong?
Thanks for any help!