Multi-fasta file: A text file file containing several DNA sequences in fasta format. Every fasta entry has 2 fundamental blocks. The first one is a single text line starting by '>' character following by a sequence description. The second block is the sequence and may contain several lines. For example: PEAKS requirements: Sequences must have the same length and only A,T,G and C nucleotides are allowed. All sequences must share a common element, such as the transcription start site, on the same position.