Geometry of arithmetically Gorenstein curves in ${\mathbb{P}}^4$

We characterize the postulation character of arithmetically Gorenstein curves in ${\mathbb{P}}^4$. We give conditions under which the curve can be realized in the form $mH-K$ on some ACM surface. Finally, we strengthen a theorem of Watanabe by showing that any general arithmetically Gorenstein curve in ${\mathbb{P}}^4$ can be obtained from a line by a series of ascending complete-intersection biliaisons.