Limiting by language...still looking

As a former German minor, and as someone who is half German and occasionally forces herself to crack open a book written in German, our catalog's language limiter bothers me a lot. I'm still looking for a way to limit by the language of an item in our OPAC. In an attempt to just retrieve things that are in German, I've tried:

ger{008}

and

ger{lang}

The first search fails. The second search acts they way the language limiter in our advanced search does, limiting the search to everything that's in German, was originally in German but has been translated into something else, has subtitles in German, has some text (but not all) in German, has librettos in German, etc. I'm going to have to dig through some help files sometime and see if there's another value I can put in the curly brackets that will do what I want.