The article examines the problem of codification of words spelling with the root ravn / rovn that allows dual motivation. Three attempts were made to reflect the variant orthographical norm for verbs in the rule, in the meaning of which there are some  components that determine the vowel  a or the vowel o in the root and the writing of which varies not only in the correct language usage, but also in the dictionaries and respected spelling manuals. The drawbacks of each of the proposed codification solutions are uncovered that fix the variability. The results of the spelling frequency study for ravn and rovn are presented in the problematic verbs. It is argued that every literate writer has his own linguistically based system for the distribution of a- and o-spellings, but these systems do not coincide. The refusal of variable spelling fixation in the rule with dual orthographic motivation is substantiated. This codification decision is considered as a continuation of the codification tradition for words with a multiple spelling motivation that was developed in the twentieth century. A draft rule on the root ravn / rovn writing  is presented, where the only spelling is indicated for problematic verbs.