Line sequential I/O allows you to access records of a text file in an established sequence. The records are stored with trailing spaces removed.
If the records are written to a line sequential file using unqualified WRITE commands, the file will be identical in format to those files produced by your operating system editor.
If the records are written to a line sequential file using qualified WRITE commands (for example using WRITE AFTER or WRITE BEFORE commands), the file will not be identical in format to those files produced by your operating system editor.