dba - standing for Dna Block Aligner, was developped by Niclas Jareborg, Richard Durbin and Ewan Birney for characterising shared regulatory regions of genomic DNA, either in upstream regions or introns of genes
The idea was that in these regions there would a series of shared motifs, perhaps with one or two insertions or deletions but between motifs there would be any length of sequence.
The subsquent model was a 3 state model which was log-odd'd ratio to a null model of their being no examples of a motif in the two sequences.