A sequence number of six digits can be used to identify each source program line.
If the first character position of the sequence number field contains an asterisk, or any nonprinting control character (less than the character SPACE in the ASCII collating sequence), then the line is treated as comment and is not output to the listing file or device. This facility allows an output listing file to be used as a source file to a subsequent compilation.
This support is sensitive to the MFCOMMENT Compiler directive.
The sequence number can contain any character in the computer's character set.