  A dominating set $S$ of a graph $G$ is called locating-dominating, LD-set for
short, if every vertex $v$ not in $S$ is uniquely determined by the set of
neighbors of $v$ belonging to $S$. Locating-dominating sets of minimum
cardinality are called $LD$-codes and the cardinality of an LD-code is the
\emph{location-domination number} $\lambda(G)$. An LD-set $S$ of a graph $G$ is
\emph{global} if it is an LD-set of both $G$ and its complement $\overline{G}$.
The \emph{global location-domination number} $\lambda_g(G)$ is the minimum
cardinality of a global LD-set of $G$.
  For any LD-set $S$ of a given graph $G$, the so-called \emph{S-associated
graph} $G^S$ is introduced. This edge-labeled bipartite graph turns out to be
very helpful to approach the study of LD-sets in graphs, particularly when $G$
is bipartite.
  This paper is mainly devoted to the study of relationships between global
LD-sets, LD-codes and the location-domination number in a graph $G$ and its
complement $\overline{G}$, when $G$ is bipartite.
