+ *
+ * @const OS_SUBCOMMAND_OPTION_FLAG_ENUM
+ * The option has an explicitly-defined list of valid inputs that are enumerated
+ * in the option's {@link osco_argument_usage} field. When printing usage
+ * information for this option, the implementation will not transform the string
+ * in this field in any way.
+ *
+ * For example, an option named "--stream" might have three valid inputs:
+ * "stdin", "stdout", and "stderr", and the usage string may be specified as
+ *
+ * "stdin|stdout|stderr"
+ *
+ * Without this flag, the implementation would print this string as a parameter
+ * name, i.e. in all caps:
+ *
+ * "<STDIN|STDOUT|STDERR>"
+ *
+ * With this flag, the string will be printed as it is given.