A modification of the FASTA multiple alignment format that allows for multiple alignments in a file. More information is on the MAUVE site.
The defline contains the following in its header:
>seqname:start-stop strand comments
>1:1-598 + chrY
TCCAAGTCGGCTTTATGTTTGCTTCTGCCAGGCATTCTAGATGCCCCATGTCTAGGATCT
CTTTAGGCAGGAGAGAGGGTGATGGTGTAGGAGGACCCATTTCTTGGCTTGCAGATTCCA
ATAATAAAAAAGTCACAGATTTAAACCCCAAACTTTGATGAAATGCAGGTCTAGGGTTTT
AAAATATAATGAGAGTTAAATACTTTTGTATTTTCTTCATCCAGAGATGGGGCAAGCTTC
CTCATCTGCTCGTTCATGGGTGATTTATATTTTCCCCACTCCATCCTTTTCCTAAGGTAT
TTTTTTTTTAGGGACAATGGCTTTTTGCAGAGTACTCAGTTCCAGCTCCGGGGGCACCGG
TTGAGCCCTTACCGTCCTGCCCCTAAACATCCAGACCTCAAGTTAGAGAGGGGAGTAACA
TTTGGGGGGTGCCCACACCTAGGAGGACCAATCCTTCTGGTTTCCTTAGGGATGCAGGAA
TTTGGGGGGGGGGGGCTCAGTGCTAAAACCAGTAGAGTCCTGGGCAAACGAGTATGACTG
AAGATGCTTTGAACACCCTAGCGTTATGTCGATCGCATGCATCGTAGTGTCGCTGATG
>2:5000-5598 - chr17
TGCAGATTGGCCTT-TGTTTCGTTTTTC-AAGCGTT-TAAA--CGCCTTGCCTAAGAATC
TTTT--GCAGGGAAGGGGATAGTGAACTGGGAAAACCTGGCTCTTCCTTTCGAGATTCCA
GTAACAAACATGTCATAACTATAAACGCCAAACTTGG--AGAGCGCAGGAATGGAAGGTC
AAACACCAATGAGAGTTAGATGGTTTTGGGTTT----------------------GCT--
CTAGTCTGCACG-------GTGCTCCCCGTCCCCTCACGTCCGTGCTTTTCCTCAGGATG
ATGCCTTGCCAGAACACCGGTGTGCTGCAAGGTGCTCAGCTCCAAATCGGGCTGCACCGC
TTCAGCTTTCCCCATCCAGCCA--ACGCAGGAAGGCCTGGAGCTACAGAGTTTAGAGCCA
TCTCTCCGCTGCTCAT--------TAACCAACCATTCCAGCT-------GTCTGTAGTGG
GTTTTTTTCTT----CTCTACACTAAAATGAGGACAGTCCAGGCCCTTTG--TTAGACTG
AAGATGCTTTGAACACCCTAGCGTTATGTCGATCGCATGCATCGTAGTGTCGCTGATG
>3:19000-19598 - chr7
TCCAGACTGTCTTT-TGCTCCCTTTTTCCGAGCATT-TAAAAATACCATGCCTAAGAATC
TTTT--GCAGGGAAGGGGATAGCGAGCTGGGAAGGCCTATTTCTTCATTTCGAGATTCTG
GTAATAAACATGTCATAAATATAAATGCCAAACTCCG--GAAATGCAGGTGTAGAGCGTC
AGATTCTATTTGGACTTAAATGATGTGGTGTTTT---------------------GCT--
CTAATTTCTACC-------GTGCTCTCCGTTCC-TCAAGTCCATGCATTTCCTTAGGGTG
CTGCCTTTCCAGAGTACTGGTATGCTGCAGGGTGCTCAGTTCCACATCTGTCTGCACTAT
TTCAAAGTTTCCC-TCCAGCCC--ACACAACTATGCCTAGAGCTA--GAGGTTAGAACCG
TCTGTCCA-TGCTCTT--------TAACCAACCACTCCAGAT-------AGGTGTGGTGG
TTTTTTTTTTTTTTTCTCTGTACTAAAATTAGGACAGTCCAGGCCTGTTG--TTAGACCA
AAGATGCTTTGAACACCCTAGCGTTATGTCGATCGCATGCATCGTAGTGTCGCTGATG
= score = 111
>1:1000-1060 + chrY
CACTCTAATAGTAAAGTTTCTTTTGCTGTGCAGAAGCTCTTTAGTTTAATTAGATCCCAT
>2:6000-6060 + chr17
CACTCTAATACTAAACTTTCTTTTCCTCTCCACA----CTTTACTTTAATTACATCCCAT
>3:20000-20060 - chr12
CACTCTAATAGTAAAGTTTCTT----TGTGCAGAAGCTCTTAGTTTTAATTAGATCCCAT
= score = 11'