+\fB\-a\fR, \fB\-\-cat\fR
+Like -t, but concatenate the files.
+.TP
+\fB\-X\fR, \fB\-\-width\fR \fIwidth\fR
+Force the output to width \fIwidth\fR. (Otherwise, the width of the master file will be used)
+.TP
+\fB\-Y\fR, \fB\-\-height\fR \fIheight\fR
+Force the output to height \fIheight\fR. (Otherwise, the height of the master file will be used)
+.TP
+\fB\-r\fR, \fB\-\-rate\fR \fIrate\fR
+Force the output to have the framerate \fIrate\fR. (Otherwise, the framerate of the master file will be used)
+.TP
+\fB\-f\fR, \fB\-\-frame\fR
+The next slave replaces a frame, not an object. Therefore the slave identifier is a
+frame number (#frame=) or frame label (framelabel=).
+.TP