() Compute all-versus-all PLAs. () Identify possible repeats by computing non-overlapping PLAs. () Generate a block of possibly alignable regions from the PLAs. () Compute a guide tree for the block. () Progressively align sequences in the block and eliminate spurious alignments using heuristic filters. () Trim the block alignment. () Discard used PLAs, and repeat the alignment process until no more alignable blocks of length at least can be found. The end result is a set of aligned regions with length at least .