Following the publication of Meillet’s Introduction in 1937, IndoEuropeanists agree in general on the phonological system of the proto language. It has been determined by application of the comparative method, the results of which are treated phonemically. The phonemes are also examined for their morphological roles, especially in verbal roots and bases. In contrast, the system given in the older standard handbooks is based essentially on phonetic analysis, extended by the procedures that Brugmann labeled purely systematic (1897: ix). This chapter presents the currently assumed system, with attention to
positions that were held in the past, as well as to disputed analyses and the bases for the disagreements. Since our view of the morphological patterning follows the formulations of Benveniste (1935), which rep resents a rigorous version of the root theory propounded already by Saussure (1879) and elaborated by others, including Meillet, we sketch it briefly.