Docbook Links

Docbook offers several forms of links: link, olink, ulink, xref Examples. This page will one day explain, which form to use in which case.

Motivation

While document internal links are easy, cross references between different documents, here Guide and Manual, are difficult.

When we supported only xml for yelp, we used URLs with the protocols
ghelp:

It searched for

/usr/[locale/]share/gnome/help/<docname>/<LANG>/<docname>.<extension>.
Important

In 2022 Yelp dropped this extension!

help:

With the XDG help-spec this was introduced, which searches

/usr/[locale/]share/help/<LANG>/<docname>/index.<extension>.
- You can still use that as shorthand under Linux like to test the german manual
```
LANG=de_DE-utf8 yelp help:gnucash-manual
```
But they do not work under other OSes or other file formats like html, chm, pdf, mobi or epub.
One approach to circumvent this issue is the use of https: in a published resource at gnucash.org. The downside: you can not read it offline.

So we will have to use olinks. Because olinks are very powerful, they a complicated, not well documented and their elements changed over the time.