support eprinttype for DigiZeitschriften Typ a

[StevanWhite]

The Deutsche digitale Zeitschriftenarchiv (German Digital Periodicals Archive) uses its own URL pattern to access articles, journals, newspapers, and series, called DZa (DigiZeitschriften Typ a).

For instance, this page is identified by a DZa pattern: https://www.digizeitschriften.de/dms/img/?PID=GDZPPN00250510X

I suggest that you add support for this kind of document identifier.

There are two types: 'img' for articles or pages, 'toc' for series or periodicals; these form part of the URL path. Only the part after 'GDZPPN' forms the identifier number.

These declarations suffice for me:

% DZa = "DigiZeitschriften Typ a"
% eprint: take only end of URL, after PPN=GDZPPN
% eprinttype: DZa; eprintclass: either img or toc
\DeclareFieldFormat{eprint:DZa}{%
  {DZa:\addcolon }
  \ifhyperref
    {\href{https://www.digizeitschriften.de/dms/\thefield{eprintclass}/?PID=GDZPPN#1}{\nolinkurl{#1}}}
    {\nolinkurl{#1}}}

This is used in a bibliography entry like so

  eprint =      {00250510X},
  eprinttype =  {DZa},
  eprintclass = {img},

to produce a URL like this http://www.digizeitschriften.de/dms/img/?PPN=GDZPPN00214123X which is displayed in the reference entry of the PDF like DZa: 00250510X.