Let's assume we want to cite the article


Our LaTeX document contains


Both DBLP and the publisher's Web page concerning the document suggest number = {4es} for BibTeX. However, we use biber in this question. Would the answer stay the same (and "4es" considered a "short designator"), or would we switch to issue = {4es}?

  • 1
    number and issue are not the same, although it's not entirely clear to me how certain journals choose these two. What is the problem you are trying to solve? Is it that biber is complaining about 4es not being only digits? Feb 11, 2019 at 3:19
  • I see there is one work citing this paper. I don't have access to the full text but maybe you can pull it up and check how it is cited there. Feb 11, 2019 at 3:34

1 Answer 1



number = {4es},

'4es' is a prime example of what those who wrote the 'short designator' passage in the biblatex manual had in mind. In fact 4es is even analogue to the example S1 mentioned in the manual (S1 is 'supplement 1' and according to the ACM digital library page of ACM Computing Surveys the es in 4es stands for 'electronic supplement').

In general, if one has to decide between number and issue, number is going to be the better choice. issue is almost never what people want.

A good rule of thumb is that number modifies (or subdivides) volume, while issue modifies the publication year. That's why examples of sensible issue usage almost always revolve around terms like issue = {Summer}, or issue = {Michaelmas term},. Numeric and semi-numeric identifiers like 4es, S1 modify the volume and should go into number.

In older versions of biblatex, number was listed as an integer field, which made some of those who read the documentation shy away from putting S1 or 4es in the number field. But that was changed following https://github.com/plk/biblatex/issues/726 and some discussion on this site (Biblatex doesn't recognize the journal's issue number when filled by a non-numeric value, Biblatex APA-style special issue code shows up in the in-text citation) and elsewhere. Of course you now can't enjoy numeric sorting by number, but you can't have your cake and eat it too. (It is possible to turn number back to an integer field in a custom data model. Technically speaking sorting of non-integer values would not be well-defined in that case, though, and so values like 4es should be avoided.)

Small aside: Whether you use BibTeX or Biber as backend for biblatex does not matter for this question. What matters is that you use biblatex and not BibTeX and its .bst styles. So the dichotomy is not 'BibTeX vs. Biber' it is 'BibTeX vs. biblatex'. For the majority of the biblatex data model and the general meaning of fields it does not matter whether you use BibTeX or Biber, but of course there are details where the two backends differ (think data model customisability, data inheritance, date field parsing, ...).


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