ddjvu: Does it really support converting to PDF?

ddjvu (DjVuLibre), 3.5.28:

ddjvu --help

returns

-format=FMT       Select output format: pbm,pgm,ppm,pnm,rle,tiff.

Note that it doesn't mention PDF. But then, why does the folowing command works and converts input DjVu file to output PDF one?

ddjvu -format=pdf -quality=85 input.djvu output.pdf