from the Astrodon website:
http://www.astrodon.com/articles_faq...ase:391,355,51
"Orientation does not matter, Gen 1 filters had a "^" marked on the edge. Gen 2 LRGB, photometric filters and narrowband filters do not. This is a recognition that orientation does not matter in terms of spectral performance...... However, for the sake of consistency during troubleshooting, you may consider mounting all filter one way or the other regarding the most reflective side."
I would assume this to be the case with Baader as well, for the same reasons as given in the article.