# biblatex-chem warning: Macro 'institution+location+date' already defined. What does it mean and how do I get rid of it?

As a rule of thumb, I aim to make my latex compilations complete without errors or warnings. I've come to accept some underful badboxes as unavoidable though :(

I'm trying to change over to biblatex, as evidence by several of my other posts.

With a rather stripped down code I am given this warning message, when I compile:

Package biblatex Warning: Macro 'institution+location+date' already defined.
(biblatex)                Using \renewbibmacro.


But don't really know what it means or how to sort it.

I can provide more info in necessary, but it could get rather cumbersome.

I am using a custom .cls file, partially handed down to me and partially modified by me. It's based on the book class. I have searched for the word "institution" in it (not as whole word only), with no success.

So if someone has some knowledge of this and how I might resolve the warning then please let me know. If you need some more info then hopefully I can help there too.

EDIT: I'm also using the chem-rsc biblatex package option.

EDIT: The following would appear to be a VERY minimal working example of the bug/feature/eccentricity:

\documentclass{book}
\usepackage[style=chem-rsc]{biblatex}
\begin{document}
\end{document}

-

From your earlier question, I infer that you are using the style chem-rsc which is part of biblatex-chem. I took a look into chem-rsc.bbx and indeed found the following code snippet:

\newbibmacro*{institution+location+date}{%
\printlist{institution}%
\newunit
\printlist{location}%
\newunit
\usebibmacro{date}%
\newunit
}


Because the institution+location+date bibmacro is already defined in the biblatex core file standard.bbx, and because chem-rsc.bbx (like most bibliography styles) eventually relates to standard.bbx, this seems to be a bug in biblatex-chem.

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Then we should change the title of this question. At the moment the relation to biblatex-chem is missing. –  Marco Daniel Sep 25 '11 at 13:43
@Marco: As soon as aghsmith confirms my suspicion, I'll add the chemstyle tag. We could also amend the question title. –  lockstep Sep 25 '11 at 13:45
In this way we increase the chance that Joseph will read this question. –  Marco Daniel Sep 25 '11 at 13:51
@lockstep, thanks for this, I think you went a bit above and beyond by checking my previous posts. I had started doing checking through all the latex packages, but missed out the chem-rsc style because it had been placed in my user area instead of the main package repository. I'd be happy to try and report this bug myself, but you found and identified it, perhaps you would like to do the honours? else I'll have a go. Cheers. –  aghsmith Sep 25 '11 at 13:57
biblatex does not issue a 'hard' error for \renew..., unlike the kernel, so these things are a bit harder to pick up. I've altered the appropriate lines, and CTAN will be updated shortly. –  Joseph Wright Sep 25 '11 at 17:35

The warning is clear. Somewhere you make something like

\newbibmacro*{institution+location+date}


but this macro already exists. So you must change it to

\renewbibmacro*{institution+location+date}

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though technically correct I was hoping for something more insightful. I was aware that I had not defined a macro by this name, myself. I had guessed that it had arisen based on a conflict within packages, possibly involving the book class, which I have since checked. I guess it did inspire me to start checking the internals of other packages, so I up voted your comment. –  aghsmith Sep 25 '11 at 13:52
@aghsmith: The problem: You haven't provide a minimal example and your information are very spare. –  Marco Daniel Sep 25 '11 at 13:56
yes this is true. I guess I was hoping that this problem would ring bells with someone and they would immediately know what the matter was. I will try and produce a minimal example as a reference. –  aghsmith Sep 25 '11 at 14:22