Comparison of multimegabase genomic dna sequences is a popular technique for finding and annotating conserved genome features . performing such comparisons entails finding many short local alignments between sequences up to tens of megabases in length 比较数兆碱基的dna序列是发现和标记保守的基因组特征普遍使用的技术，进行这样的比较可以发现长达几十兆的序列之间很多短的局部对齐。
