We have stressed that the gusheh is a kind of melodic model or a melodic framework, more or less elaborated depending upon the master from whom one learns it. The musician may alter and embellish the gusheh at will, and, theoretically, he performs it in a different way each time he plays. According to his feelings of the moment, the player creates a highly personal and intimate performance by varying and adding to the basic gusheh.
Thus, one may think of a gusheh as consisting of two sets of elements—one set of fixed elements and another set that varies for each performer and for each performance. These two sets of elements were identified over a thousand years ago by the philosopher and theorist al-Farabi: "Les éléments qui nous permettent de réaliser une mélodie sont de deux sortes: les uns constituent son existence essentielle; les autres rendent son existence plus parfaite. Il en est d'une mélodie comme de tout être né de l'association de plusieurs choses. Les éléments indispensables à sa réalisation sont les notes de l'espèce choisie et quant à ceux qui la rendent plus parfaite, les uns l'enrichissent d'autres y ajoutent des ornements ou de l'emphase."
The fixed elements of the gusheh make up the model: the location and configuration of the tetrachord, the melodic function of each scale degree, the melodic shape, and characteristic cadence formulae. Illustrating these fixed elements is the melody for the initial gusheh of Shur, the daramad. Located in the lowest part of the Shur range, the daramad encompasses the tetrachord C C Eb F, which contains two neutral seconds, C to D-koron and D-koron to Ε-flat. The shahed and the ist are both the tonic note, C. The melody, in most versions, first stresses the C, then outlines the descent from the third and fourth notes to C, and again stresses this note. Its contour is primarily descending. This is the melodic model or the set of fixed elements for the daramad of Shur.11 In an improvised performance, they would be recognizable.