# Add new field to biblatex entries

Many of the books I use are parts of series. `biblatex` gives you more fields to add bibliographic information to than BibTeX does, but it has no fields appropriate for the editor of a series. If I use the `EDITOR` field, the bibliography will (by default) print `edited by`, which doesn't give the right impression of what the role of the series editor is.

I'm wondering if there is any easy way to add a new field `SERIESEDITOR`, which will make `biblatex` by default print its content preceded by `Series edited by` or make sure that whatever is in `SERIESEDITOR` gets printed directly after the name of the series, such that is says something like `[Name of series], edited by [series editor]`. In other words, is there any way I can do this in the preamble of my document, without having to venture into writing new bibliography styles?

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I guess there is some reason not to do it the obvious way which (I take it) involves adding a few strings to a `biblatex.cfg` and then using `editor` with `editortype` or the `a` `b` or `c` versions of same? (Maybe this wasn't available when this was asked?) – cfr Sep 17 '15 at 23:57
@cfr Obvious to whom? `:)` I know nothing about `biblatex.cfg`, plus I'm skeptical of messing with the internal files of `biblatex`. – Sverre Sep 18 '15 at 9:22
Well, it's a config file. I just use the standard interface for it. That is, Biblatex is designed so that certain things can be extended according to need because nobody could anticipate, say, all possible relations between entries or all possible roles. At least, that's how I understand this bit of what my `*.cfg` does. (It does some other things which might count as messing with the internals, but not this, I don't think.) – cfr Sep 18 '15 at 11:42

`biblatex 2.0+` and `biber 1.0+` allow you to define additional fields and entry types, but this is intended for style authors and can't be used in the document preamble.

With `biber`'s source map feature you can however use the field `serieseditor` and map it to a field defined in the default data model, such as `namea`. This existing field can then be printed in the bibliography macro that sets the `series` field.

``````\DeclareSourcemap{
\maps[datatype=bibtex]{
\map{
\step[fieldsource=serieseditor,fieldtarget=namea]
}
}
}

\renewbibmacro*{series+number}{%
\printfield{series}%
\printfield{number}%
\ifnameundef{namea}
{}
Since version 2 (and in combination with `biber`, version 1 or greater) `biblatex` allows you define any kind of additional field. Check out chapter 4.5.2 of the `biblatex` manual.
I did look there, but I didn't, and don't, understand what I need to do to make `biblatex` parse a field I've added to my entries. – Sverre Jul 31 '12 at 19:01
To have `biblatex` parse it you must of course adapt the style files. For example, if you add a field `serieseditor`, you must look which parts of the .bbx/.cbx should handle this field and write the needed adaptation. – Simifilm Jul 31 '12 at 19:26