[TYPO3-Solr] Add relations to files

[Marco Bresch]

Hi all,
is it possible to add custom fields while indexing files?

In my case I would like to use category_stringM for tt_news related 
files too.

For example: My news has a category named CatA and contains a file 
document.pdf. So the facet CatA should be available when document.pdf is 
found.

Thanks for help and best regards
Marco :-)

(EAP - 2.6.0 at the moment)