Using xlink:href as you describe is considered the proper way in MODS to
reference an authority. A related example is in the MARC 21 to MODS mapping
(, which shows that
subfield 0 (zero) in MARC 21 is equivalent to use of the xlink attribute in

However, xlink can be used in a MODS record for a variety of external
linking purposes, some of them having nothing to do with authority records
or authority URIs. That seems to me to present problems for processing a
MODS record. I wonder if MODS users will find they want a more specific
attribute defined that can only contain an authority URI. So, I'm not
convinced that use of xlink is the best practice in the long term for
encoding a link to an authority URI. I will raise this issue with the
MODS/MADS Editorial Committee.

Joe Altimus
Arizona State University Libraries

On Thu, Feb 19, 2009 at 1:51 AM, Neubert Joachim <[log in to unmask]> wrote:

>  We are mapping data to MODS record structures (from a PICA library system
> via Marc21 interface) . This includes various kind of authority data, eg.
> subjects, persons etc. For subjects, the authority data is in SKOS.
> (Thesaurus for Economics, preview on It is
> based on concepts with an URI as persistent identifier. The concepts have
> prefered labels in German and English, which should be present in the MODS
> records for display and indexing convenience.
> What we figured out as a possible solution is this:
> <subject authority="stw" xlink:href=""
> lang="en">
>   <topic>Financial crisis</topic>
> </subject>
> <subject authority="stw" xlink:href=""
> lang="de">
>   <topic>Finanzmarktkrise</topic>
> </subject>
> (We don't really like the de-normalized form. Much better would be:
> <subject authority="stw" xlink:href="
> ">
>   <topic lang="en">Financial crisis</topic>
>   <topic lang="de">Finanzmarktkrise</topic>
> </subject>
> However, that's invalid in MODS 3.3)
> What do you think - is it ok to use xlink:href for the reference to the
> authority record?
> Since we are new in the MODS field, we wonder if there is are other
> solutions or best practices for this we may not be aware of.
> Cheers, Joachim
> --
> Joachim Neubert
> IT Development
> German National Library of Economics (ZBW)