You may break the progress of a pattern at any time by pressing the , (comma) key after it has been started. The word <break> will then appear in the row (as shown in Figure 3.5).
A Pattern Break may also be used to undo a Pattern Mute or a Pattern Thru further in the sequence. So entering a mute after a pattern of a tracker which plays a long speech sample, two bars later a break, two bars later a mute, a break, etc, will result in that speech sample played in parts of 32 ticks (when step value is set to 16, as it is by default).
Figure 3.5