Gwoyeu Romatzyh
Even though many other Asian languages use tonal spelling, like Hmong, they all represent tones by using the same letter each time the tone is used. In Hmong, for example, -b is always a high tone, -s is always a low tone, -j is always high-falling tone. In GR, however, each syllable final has its own spelling rules, and many exceptions exist within these rules. For example, first tone words with the final -a as in bā is written with just one vowel like ba, except when the syllable begins with an l-, m-, or n-, which then must be written as lha, mha, and nha respectively. This is only one of its many rules and exceptions.