Relaxed joliet filename lengths in DeepBurner?

I am burning (non-media) file trees to DVD. The DeepBurner help has a
featues section that says filenames can be 255 characters. My longest
pathname is 187 characters, but DeepBurner still complains about
overly long names. I can't find a switch to enable 255 characters.
Is it 255 by default? If not, how does one set it to 255?

Thanks!