+/** \file adu.c \brief The main functions used by all modes of operation. */
+
+/**
+ * \mainpage adu API reference
+ *
+ * - Modes of operation: \ref select.c, \ref create.c, \ref interactive.c
+ * - User handling: \ref user.c
+ * - Error handling: \ref error.h
+ * - Library-type functions: \ref fd.c, \ref format.c, \ref string.c, \ref portable_io.h
+ */
+