[Tex/LaTex] BibTeX warning that optional fields are empty

bibtexwarnings

I've got the following .bib file (Material.bib):

@manual{GHCUserGuide,
  author = {The GHC Team},
  title = {The Glorious Glasgow Haskell Compilation System User's Guide},
  number = {7.6.3},
  institution={University Court of the University of Glasgow},
  year = {2013},
  month = {April}
}

@techreport{Haskell_1_3,
  author = {John Peterson and others},
  title = {Report on the Programming Language Haskell},
  institution = {Various institutions},
  year = {1996},
  month = {May}
}

and the following tex file: 

\documentclass{scrreprt}

\begin{document}

\nocite{Haskell_1_3}
\nocite{GHCUserGuide}

\bibliographystyle{alphadin}
\bibliography{Material}


\end{document}

When running BibTeX, I get the following warnings:

This is BibTeX, Version 0.99d (MiKTeX 2.9)
The top-level auxiliary file: BibTeX.aux
The style file: alphadin.bst
Database file #1: Material.bib
Warning--empty number in Haskell_1_3
Warning--empty note in Haskell_1_3
Warning--empty edition in GHCUserGuide
Warning--empty address in GHCUserGuide
(There were 4 warnings)

That's strange because all the mentioned fields in the output are optional and not required for the given entry types. What's the reason for this behaviour and is there any way to get rid of the warning messages without having to add the fields to the .bib-file?

Best Answer

The alphadin.bst file is present in TeX Live

/usr/local/texlive/2013/texmf-dist/bibtex/bst/din1505/alphadin.bst

and it uses slightly different rules for the fields. The classification of fields into mandatory and optional for a particular entry type depends on the bibliography style. It happens that alphadin.bst requires those fields for those entry types, so BibTeX warns when it doesn't find them.

The documentation about the din1505 styles can be found at

http://mirror.ctan.org/biblio/bibtex/contrib/german/din1505/normpatsoft.pdf

and its title is

Bibtex–Beispiele für Normen, Patente und Software nach Abschnitt 6.4, 6.5 und 6.8 der Norm DIN 1505 Teil 2

so they seem very specialized bibliography styles, for which it's clear that particular rules are applied.

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