Vowel harmony in Hungarian is most notable when observing suffixation. Vowel harmony must be maintained throughout the entire word, meaning that most suffixes have variants. For example, the dative case marker vs. . Stems that contain back vowels affix back vowel suffixes, and stems that contain only front vowels affix front vowel suffixes. However, the front vowel stems distinguish rounded vs. unroundedness based on the last vowel in the stem. If the last vowel is front and rounded, it takes a suffix with a front rounded vowel; otherwise it follows the standard rules. While suffixes for most words have front/back vowel variants, there are not many that have rounded/unrounded variants, indicating that this is a rarer occurrence.