This work comprises a number of modules, most of which are repeated, ad libitum, except in the case of letter B which has a different repetition structure (see below) and the final two bars which are played once only.
The tempo increases very gradually during the performance from crotchet=144 to crotchet=220 by six bars before G. Thereafter, tempo changes are proportional.
Dynamics are not marked. This is to allow the performer to choose the dynamic "according to the moment". In general, however, sharp changes of dynamics should not occur.
Between bars means repeat those bars ad libitum changing the order of the bars also ad lib. Each bar may be played one or more times before moving on to another.
Some pitches are bracketed to give an opportunity for breathing - but if it is not necessary to breathe at that point, then play the pitch. The sound should be as continuous as possible, but without obvious strain.
Bracketed slurs (as in the 5th module of F) are intended as suggestions: the performer can play different "versions" as a bridge between the different articulations of the previous and the ensuing bars. Pitches with a "x" notehead are to be sung (not through the instrument).From Melvyn Poore's Performance Notes