  We introduce the metric space valued in partially ordered groups, and define
the convergence of sequences and the multi-valued weak contractions, etc., on
the space. We then establish endpoint theorems for the defined maps. Our
contributions extend the theory of cone metric space constructed by Huang and
Zhang (2007) and some recent results on the fixed point and endpoint theory,
such as the endpoint theorem given by Amini-Harandi (2010).
