Verbs that begin with a vowel rather than a consonant are called I-weak. Verbs beginning with the approximants "n" and "y", which were susceptible to assimilation in Classical Mandaic, have been reformed on the analogy of the strong verbs. When they appear as the second or third radical of a consonantal root, the liquids "w" and "y" are susceptible to the general collapse of diphthongs described above. The verbs that are thus affected are known as II-weak and III-weak verbs. Those roots in which the second and third radical consonants were identical have been reformed on the analogy of the II-weak verbs; this process had already begun in Classical Mandaic.