\fB\-u\fR, \fB\-\-update\fR
Append files which are newer than the corresponding copy in the
archive. Arguments have the same meaning as with \fB\-c\fR and
-\fB\-r\fR options.
+\fB\-r\fR options. Notice, that newer files don't replace their
+old archive copies, but instead are appended to the end of archive.
+The resulting archive can thus contain several members of the
+same name, corresponding to various versions of the same file.
.TP
\fB\-x\fR, \fB\-\-extract\fR, \fB\-\-get\fR
Extract files from an archive. Arguments are optional. When given,
updating it.
The reason @command{tar} does not overwrite the older file when updating
-it is because writing to the middle of a section of tape is a difficult
+it is that writing to the middle of a section of tape is a difficult
process. Tapes are not designed to go backward. @xref{Media}, for more
information about tapes.