Po4a extracts the translatable material from its input in a PO file.
When the PO file is translated, it re-injects the translation in the structure of the document,
and generates the translated document.
If a string is not translated (i.e. it was not translated or it is "fuzzy"
because the original document was updated), the original string is used.
This permits to provide always up-to-date documentation.

po4a supports currently the following formats:
* manpages
* POD
* XML (generic, DocBook, XHTML, Dia, Guide, or WML)
* SGML
* TeX (generic, LaTeX, BibTex or Texinfo)
* text (simple text files with some formatting, markdown, rubydoc or AsciiDoc)
* INI
* YAML
* KernelHelp