「轉」仲分爲內外兩種類型。外轉就係包括純二等韻嘅轉，無純二等韻嘅即係內轉。純二等韻就係依韻母分等嘅二等。相對，依聲母分等嘅二等被稱爲假二等。現在學界傾向於認為：純二等字有一種特殊嘅介音——在音位上可以寫成/r/。這個介音由上古音的聲母後加成分墊介音/r/轉化而來。佢喺中古音裏邊嘅真實音值尚無定論，但佢作為一個音位係顯然存在的，且性質毋同於以往分析出來嘅介音 -i-和-u-。佢嘅特殊之處就在於：憑其有無即可使韻圖分出內外兩轉以及造成韻書中重紐嘅現象，但是又不能通過聲韻相拼的反切將其音位特徵嚴密噉表述出來。
There are also two types of "turning", both inside and outside. The outward transfer is the rotation that includes the pure second-class rhyme, and the inward transfer without the pure second-class rhyme. Pure second-class rhyme is the second-class rhyme that is graded according to the rhyme master. In contrast, the second class according to the initials is called false second class. Nowadays, scholars tend to believe that pure second-class characters have a special intersonant - they can be written as /r/ on phonemes. This consonant is converted from the initial consonant of the archaic sound followed by the component pad /r/. The true value of his middle sound is inconclusive, but his existence as a phoneme is clearly inconclusive, and its properties are not as good as those of the previously analyzed mediates -i- and -u-. His peculiarity lies in the fact that the rhyme diagram can be divided into internal and external turns and the phenomenon of repeating the rhyme by virtue of its presence or not, but it cannot be strictly expressed through the reverse cut of the rhyme.