  A quadratic Lie algebra is a Lie algebra endowed with a symmetric, invariant
and non degenerate bilinear form; such a bilinear form is called an invariant
metric. The aim of this work is to describe the general structure of those
central extensions of quadratic Lie algebras which in turn have
invariantmetrics. The structure is such that the central extensions can be
described algebraically in terms of the original quadratic Lie algebra, and
geometrically in terms of the direct sum decompositions that the invariant
metrics involvedgive rise to.
