Abstract :
A multilevel multichannel R-matrix package has been developed to describe resonant nuclear cross sections, that are useful for light elements nucleosynthesis. Several options can be set to take care of interfering levels either as accurately as possible, either in an approximate way. To take care of a direct component and/or external levels one can use fictitious levels or adjust the interaction radii. To avoid to deal with partial widths associated with non measured reactions, an eliminated channel can be set.
