 This is the reversible block-sort that is at the core of bzip2.The block is entirely self-contained, with input and output buffers remaining of the same size—in bzip2, the operating limit for this stage is For the block-sort, a (notional) matrix is created, in which row "i" contains the whole of the buffer, rotated to start from the "i"-th symbol.Following rotation, the rows of the matrix are sorted into alphabetic (numerical) order.