Within the context of Virtual Observatory, the "Atomic and Molecular Line Data Model" has been developped. The main objective of the model is to give access to the relevant information that will allow the identification and search of lines within VO environments.
In the astrophysical sense, a line is considered as the result of a transition between two levels. Under the basis of this assumption, a whole set of objects and attributes have been derived to define properly the necessary information to deal with lines appearing in astrophysical contexts.
