  In a signed graph each edge has a sign, $+1$ or $-1$. We introduce in the
present paper a new definition of connection in a signed graph by the existence
of both positive and negative chains between vertices. We prove some results
and properties of this definition, such as sign components, sign articulation
vertices, and sign isthmi, and we compare them to corresponding graph and
signed-graphic matroid properties. We apply our results to signed graphs
without positive cycles. For signed graphs in which every edge is negative our
properties become parity properties.
