+(Note that your shell may also take an interest in backslashes,
+particularly under Unix. You may find that the backslash with which
+you escape a colon must be doubled in order to make the shell pass
+it to Halibut at all, and to pass a doubled backslash to Halibut you
+might have to type four backslashes on your shell command line. This
+is not part of Halibut's own behaviour, and it cannot do anything
+about it.)
+