[arch-general] PKGBUILD depends - howto specify alternate packages that can satisfy? possible?

Guys, I am trying to create a PKGBUILD that needs qt3, but I want to make it flexible enough to accept either 'qt3' or 'qt3-enhanced' as a dependency. Can I do that? I looked over https://wiki.archlinux.org/index.php/PKGBUILD and I either missed a way to do it, or I'm just confused. What say the gurus? -- David C. Rankin, J.D.,P.E.