Portable files are arranged as a series of lines of exactly 80 characters each. Each line is terminated by a carriage-return, line-feed sequence “new-lines”). New-lines are only used to avoid line length limits imposed by some OSes; they are not meaningful.
The file must be terminated with a Z character. In addition, if the final line in the file does not have exactly 80 characters, then it is padded on the right with Z characters. (The file contents may be in any character set; the file contains a description of its own character set, as explained in the next section. Therefore, the Z character is not necessarily an ASCII Z.)
For the rest of the description of the portable file format, new-lines and the trailing Zs will be ignored, as if they did not exist, because they are not an important part of understanding the file contents.