DCSE provides a user-friendly package for the creation and editing of sequence alignments. The program runs on different platforms, including microcomputers and workstations. Apart from available hardware, the program is not limited in the size of the alignment it can handle. It deviates more from classical text editors than other available sequence editors because it uses a different approach towards editing. It shifts characters or entire blocks of aligned characters, rather than inserting or deleting gaps in the sequences. Alignment of a new sequence to an existing alignment is partly automated. Although DCSE can be used on protein sequence alignments, it is especially targeted at the examination of RNA. The secondary structure for every sequence can be incorporated easily in the alignment. DCSE also has extensive built-in support for finding and checking secondary structure elements. A sophisticated system of markers allows notation of special positions in an alignment. This system can be used to store information such as the position of hidden breaks, introns and tertiary structure interactions.