The codified norm can’t fundamentally coincide with the modern practice. The codified norm is the result of the work of scientists and is intended not only to reflect the spontaneously established norm, depending on collective thinking and spontaneous standardization processes, but also to correct it in accordance with the chosen goal of the codifier. The codifier thereby not only fixes the established (or not developed) custom, but creates conditions for the realization of that potency of the writing system, the scenario of development that seems preferable to it. This preference should be theoretically justified. Choosing a particular spelling as a norm for a literate person, spelling codifiers take into account a number of factors, including compliance with the system, the current ratio of its dichotomies, the system development vector, and the practice of writing. These factors are not built into a hierarchy, often they involve different solutions. Therefore, the codifier is forced to give preference to a particular factor. What factors were preferable for the author of the dictionaries for a century? Why did they change the codified spelling? What factors prevail with years? In this paper, we analyze the types of vocabulary divergences and ways of their unification throughout the 20th century. The material is limited to the data of the Consolidated Dictionary and some dictionaries of recent decades. The article describes only the material relating to the sound-letter varieties caused by the contradiction between systemic and practical factors. An analysis of the material showed that the initial fixation, based on an criterion of practice, contradicting the systemic criterion, was gradually replaced by a system variant. This allows today and among the many of the usual options to choose with greater hope for success is the system options.