[XeTeX] Hyphenation exceptions for German -- how?

[Arno Trautmann]

Ross Moore wrote:
> Hello Arno,
>
> On 14/07/2011, at 6:38 AM, Arno Trautmann wrote:
>
>> Hi Thomas,
>>
>> short answer: use \hyphenation after \begin{document}, then it works.
>> However, I've been wondering for a while now why this is the case – can someone explain this behaviour?
>
> It could well be that the hyphenation patterns defined using
> polyglossia are not actually loaded until the \begin{document}
> by loading the appropriate commands using
>    \AtBeginDocument{... whatever ...}

Yes, apparently … but /why/?

> You can use this too, within the preamble, by doing:
>
> \AtBeginDocument{\hyphenation{%
> einer
> Me-ta-ethik
> }}

d'oh … I have to admit, I've never thought about using AtBeginDocument 
for this … more convenient than putting it after \begin{document}, indeed.

cheers
Arno