Of practical reasons each type of bleaching stage has got a special letter, Table 10.1. By combining
these letters according to some special rules it is easy to understand how the bleaching sequence
is designed. Thus, a sequence using chlorine in the first stage, alkaline extraction in the
second and chlorine dioxide in the third stage the sequence will be: CED. However, if two chemicals
are used together in the same stage the two letters from the table are written together within
parenthesis and in some cases with a plus between. If for example both chlorine and chlorine dioxide
are used in the same stage and if they are charged at the same time the stage is denoted as