BibTeX allows the user to store his citation data in generic form, while printing citations in a document in the form specified by a BibTeX style, to be specified in the document itself (one often needs a LaTeX citation-style package, such as natbib as well). BibTeX itself is an ASCII-only program; there is, however, a version that copes with 8-bit character sets. However, BibTeX’s facilities rapidly run out as one moves away from simple ASCII (for example, in the various national sorting rules for languages expressed in different parts of ISO-8859 — the “ISO Latin” series). For more flexibility, the user is urged to consider using biber with BibLaTeX to typeset its output. In fact, it is best to avoid BibTeX in favour of biber and BibLaTeX, if at all possible.