/r/ or 'ລ' /l/ as in . Letters also are more circular or rounded than the typically angled style of Khmer. Consonants There are 43 Tai Tham consonants. They are divided into three groups: categorized consonants (ᨻ᩠ᨿᩢᨬ᩠ᨩᨶᨶᩲᩅᩢᨣ᩠ᨣ᩼, payanjana​ nai wak), non-categorized consonants (ᨻ᩠ᨿᩢᨬ᩠ᨩᨶᩋᩅᩢᨣ᩠ᨣ᩼, ), and additional consonants (ᨻ᩠ᨿᩢᨬ᩠ᨩᨶᨲᩮᩬᩥ᩵ᨾ, payanjana tueam). Categorized consonants and non-categorized consonants are those derived from Old Mon script used for Pali and Sanskrit languages. Similar to Devanagari, Pallava script, and Burmese script, categorized consonants are divided into 5 subgroups called wak (ᩅᩢᨣ᩠ᨣ᩼) i.e., wak ka (ᨠ), wak ja​ (ᨧ), wak rata (ᨭ), wak ta (ᨲ), and wak pa (ᨷ). The additional consonants are the consonants invented to write Tai sounds that are originally not found in Pali. In a dictionary, letter ᩂ​ and ᩄ are often put in the consonant list following the letter ᩁ and ᩃ respectively. However, they are a syllabary (also a vowel) and not a consonant letter. Consonant chart There are 25 categorized consonants, 10 non-categorized consonants, and 8 additional consonants. Similar to Khmer, Tai Tham also has a subjoined form called haang (ᩉᩣ᩠ᨦ), tua joeng (ᨲ᩠ᩅᩫᨩᩮᩥ᩠ᨦ), or tua hoy (ᨲ᩠ᩅᩫᩉᩬ᩠ᨿ᩶). In the Unicode input method, sakot sign (U1A60) (◌᩠) is used to trigger the subjoined forms. The additional consonants are shown in yellow. These consonants have the characteristics of lacking the subjoined form. Similar to Thai script and Lao script, consonants in Tai Tham can be classified into high, mid, and low classes regarding to the tone rules. Notes Consonant combinations and ligatures Consonant digraph with Ha Certain consonants in the low-class group lack their high-class counterpart. These consonants are sometimes called the single low-class consonants. Their high-class counterparts are created by the combination with letter high Ha (ᩉ) as a digraph, called Ha Nam (ᩉ​ ᨶᩣᩴ). Notes Special letters Notes Vowels Vowel characters come in two forms: as stand-alone letters for writing initial vowels or as diacritics that can be attached to all sides of the consonant letters. However, Lanna excels in terms of the number of diacritics used. Some vowel sounds can be written with a combination of as many as four diacritics: one on each side of the consonant. Dependent vowels Independent vowels Independent vowels are mainly reserved for writing Pali words, except for /ʔau/ which is used as a special vowel sign and not for Pali words. Tone marks Tone mark conjugation There are six phonemic tones