+A semicolon (@samp{;}) can be used anywhere on a line to start a
+comment that extends to the end of the line.
+
+If a @samp{#} appears as the first character of a line, the whole line
+is treated as a comment, but in this case the line could also be a
+logical line number directive (@pxref{Comments}) or a preprocessor
+control command (@pxref{Preprocessing}).
+