- * On failure (status codes
- * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT` and
- * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR`), this function sets `*error`,
- * if not `NULL`, to a descriptive error string. Free `*error` with
- * free().
+ * On failure, this function:
+ *
+ * * Returns one of:
+ *
+ * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT`:
+ * Unknown option (not found in `descrs` as passed to
+ * argpar_iter_create() to create `iter`).
+ *
+ * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_MISSING_OPT_ARG`:
+ * Missing option argument.
+ *
+ * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_INVALID_ARG`:
+ * Invalid argument.
+ *
+ * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_UNEXPECTED_OPT_ARG`:
+ * Unexpected option argument.
+ *
+ * `ARGPAR_ITER_PARSE_NEXT_STATUS_ERROR_MEMORY`:
+ * Memory error.