+/*
+ * Option helper structure:
+ *
+ * oh_nam is left-hand part of <option>[=<value>]
+ * oh_fnc is handler function
+ * oh_arg is an optional arg to oh_fnc
+ * oh_usage is the one-line usage string related to the option,
+ * which is assumed to start with <option>[=<value>]
+ *
+ * please leave valid options in the structure, and optionally #ifdef
+ * their processing inside the helper, so that reasonable and helpful
+ * error messages can be generated if a disabled option is requested.
+ */