Complex Depends

[David Everly <david.everly@adelphia.net>]

Hello Debian Mentors,

How do I construct a "Depends" line in debian/control for the following
example:

   Require package-a or package-b.

   If package-a is selected, require package-1 and package-2.

   If package-b is selected, require package-3.

Notes:

   package-a, package-b, package-1, package-2, and package-3 are
   not under my control.

   package-1, package-2, and package-3 do not depend on package-a or
   package-b.

What I think I want to do is probably not supported (or is it?):

   Depends: (package-a,package-1,package-2) | (package-b,package-3)

Thanks,
Dave.
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