Why do publishers offer a variety of formats of electronic publications?
Most core journals in astronomy are now available in three formats: PostScript (PS), Portable Data Format (PDF) and HyperText Markup Language (HTML). In order to use PDF files, you need the Adobe Acrobat viewer which has been installed ESO-wide. PS and PDF are mainly used for printing purposes as they are capable of maintaining the format users are familiar with from the journal’s print edition. HTML is important for quickly locating a particular section within a document as well as for interlinking electronic resources (e.g., linking the references of an electronic article to corresponding abstracts in the ADS system, to SIMBAD objects, etc). HTML typically is derived from the underlying SGML (Standard General Markup Language) format. The use of a non-proprietary, richly-tagged format such as SGML is essential for interconnecting resources and for archiving purposes.
