Edit Brush Dialog Box - Spacing Tab
These options let you alter the spacing between objects in the brush. In all cases 100% is the spacing intended by the designer of the brush.
Spacing
Give regular spacing. For example 110% spaces each object at 110% of its original distance.
Random
Gives a random distance between objects. The slider limits the distance; for example, 50-200% limits the distance to between 50% to 200% of the original distance.
Sequence progresses
Suppose you have a brush design of -->.
Forward: the line looks like -->-->-->
Backward: the line looks like <--<--<--
Mirror: the line looks like --><----> (alternative designs reversed)
Random: random reverses.
Randomize
Generate a new random set of distances or sequence changes. (This button applies to both Random options.) If you prefer the previous values, click Undo.