The aligned NBRF/PIR format read and written by Multalign Viewer is a simple variant of standard NBRF/PIR format. To make an aligned NBRF/PIR file, individual sequences in NBRF/PIR format are concatenated together and made the same length by including characters for leading, trailing, and gap positions. For the purposes of Multalign Viewer, any non-alphanumeric characters except asterisk (*) are tolerated in these positions. In rhod.pir, for example, the single gap position is indicated by a dash (-). The second line for each sequence is required, but may be blank; if it is omitted, the first line of sequence will be interpreted as comments and left out of the sequence. Spaces within sequences are ignored.