Markedness constraints (in Optimality Theory) express "unfavoured" segments or syllable structures, e.g. nasalized vowels as opposed to oral vowels, front rounded vowels as opposed to front unrounded vowels, coda consonants (as opposed to open syllables), complex onsets, etc. If a language has the marked object (e.g. nasalized vowels) the language also has the unmarked object (i.e. oral vowels), while the reverse does not hold. Markedness is also relevant in morphology, e.g. passive voice is marked compared to the active voice; plural is marked compared to singular, etc.