Who has never been up against technical or computer science instructions where the authors have used different terms to describe the same functions or elements? We find the same occurrence in the theory of piano technique even though in this case it has nothing to do with negligence, but rather a lack of knowledge concerning the works of other authors.
Cz. Sielużycki (►Bibliography) adds to one of his subtitles - “Rotating movement of the arm («wing» movement)” - the following comment: “integral spindle movement of the arms (Spindelbewegung) according to Gát and, probably, (underlined by me, AW) the oblique movement of the arm according to Ching.”* The presence of “probably” indicates that Sielużycki himself was not certain of the exact terms.
* Czesław Sielużycki - “The pianist’s hand” p. 168, Polish Music Edition, Cracow, 1982 (in Polish only)