The presence of syncopation in certain words in the Libro de Alexandre (lazrar, menestral, ofrecer, sabroso, sombra, etc.) and its absence in other words (avellana, eredad, eredar, etc.) support the Castilian origin of the poem and discredit the theory of western or Leonese authorship. The preservation of the etymological medial -d- in such words as porfidia, piedes, and vidieron is also dialectically significant, since the trait is particularly evident in other documents of the area of La Rioja. Similarities between the alterations introduced into Berceo's MSS and those found in the Alex are constantly stressed, since only through a clear understanding of the problems of transcription of medieval codices can we hope to clarify the question of regular meter in mester de clerecía of the thirteenth century. Scribes were capable of completely eradicating such forms as piedes (in O), udió, udién, and meydía (in both P and O). This type of obliteration has tended to confuse many critics, who are prone to base their ideas concerning the language and versification of the Alex on the MSS as they observe them, without attempting any critical analysis or reconstruction.