Often, the versions which appear on the Web are lengthier, since the editors are not bound by the space constraints of the print version. Cited references can be linked directly to the publications they list, and images for which the printed magazine has no space can be included in the Web version. Correspondence and feedback can be linked to the appropriate articles. In addition, a considerable body of material appears in the Web version only. The first issue of the print and Web magazine appeared in January 1996.
Issues appear regularly every two months, with occasional updates to the Web version.