HyperCard under UNIX?

[HAFREE%KOESS@gmr.com (Howard Free)]

 I know this isn't the "right" place to ask, but I don't know where else to
 look.

 I'm looking for a HyperCard clone for UNIX boxes; preferably one that uses
 the same file formats, but that is not essential.

 Any clues, pointers, references or hints would be appreciated.

 (You may want to mail replies directly to me as this isn't Symbolics
 related.)

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 Howard Free
 Delco Electronics
 Kokomo IN 46904-9005
 HFREE@GMR.COM