A supercontig is formed when an association can be made between two contigs that have no sequence overlap. This commonly occurs using information obtained from paired plasmid ends. For example, both ends of a BAC clone are sequenced. It can be inferred that these two sequences are approximately 150-200 Kb apart (based on the average size of a BAC). If the sequence from one end is found in a particular sequence contig, and the sequence from the other end is found in a different sequence contig, the two sequence contigs are said to be linked. In general, it is useful to have end sequences from more than one clone to provide evidence for linkage.