Journal are only published online. We are now introducing two additional online-only sections. • The new Sect. 15, entitled "Numerical methods and codes", will be devoted to publishing new numerical algorithms and codes of interest to a sufficiently large fraction of the astronomical community. Papers submitted for the new section will emphasize the novel aspects of the featured method or code and will include an indepth description of the algorithm and/or code. The described code must be fully

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... tested and stable, and must be validated either by comparing numerical results obtained with the code with analytical solutions and/or by running benchmark comparisons with similar codes if such a possibility exists, or by comparison with experimental work. While no application to any particular astrophysical problem will be required for these papers, the ability of the method or code to successfully address complex numerical problems of astronomical interest should be clearly demonstrated in the validation section. We will first consider for Sect. 15 validated and documented codes that are ready to be released for use by the community, in which case the documented source will be made available at the CDS. We will also welcome in Sect. 15 the description and validation of proprietary codes that are not meant for release to the community if they are at the heart of numerical applications intended for publication. However, we strongly encourage our contributors to consider sharing their theoretical astrophysical tools with the community. • Section 12 "Atomic, nuclear, and molecular data" will be published online only from 2008 on, as suggested by a sizable fraction of respondents to the recent A&A author survey. The four online-only sections of A&A have topics of potential use by a wide range of astronomers. The abstracts of papers published in these sections will continue to be included in the printed edition of the Journal. Thanks to the generosity of our publisher, who provides open access to the online-only sections and to A&A Letters, these important parts of our Journal are now freely available to the worldwide community of astronomers. Article published by EDP Sciences and available at