The corpus of Bactrian, of which KI forms the most important part, is too restricted to enable us to form even a remotely complete picture of its phonemic system and development. This would be the case even if every word had been finally or at any rate plausibly interpreted. As long as we restrict ourselves to the SK inscriptions, the language seems to represent, in the main, one single dialect. But if we include in the term Bactrian everything written in Ir. language and Greek script, from the coins of Kadphises I down to the IT of A.D. 866, it seems reasonable to assume that dialect variants, of chronological or local nature, are to be found. In this paper I shall be dealing mainly with the KI, with only occasional references to other sources. For the interpretation I shall base myself on the work of Henning, Benveniste, and Gershevitch, together with the contributions made by Harmatta and Humbach; and it will be assumed that the reader is conversant with, above all, Henning's interpretation of a substantial part of the text of the inscription.