Re: Question to Slovak Wikipedia SW

during a translation of LanguageSk.php we found out a variable:
"linktrail"		=> "/^([a-z]+)(.*)\$/sD"

When is this variable used?
Do I need to provide our national RegEx?
If yes, could somebody post a link to used RegEx's? Or just regular PHP 
RegEx's are used (not working with PHP deeply - I have no detailed info 
about it)?
Would be helpful to add a few comments to language file - for better 
orientation of translator.

Any help is welcomed!

Best wishes
-- stanislav valasek