-extern struct sr_output_format output_text_bits;
-extern struct sr_output_format output_text_hex;
-extern struct sr_output_format output_text_ascii;
-extern struct sr_output_format output_binary;
-extern struct sr_output_format output_vcd;
-extern struct sr_output_format output_ols;
-extern struct sr_output_format output_gnuplot;
-extern struct sr_output_format output_chronovu_la8;
-extern struct sr_output_format output_csv;
-/* extern struct sr_output_format output_analog_bits; */
-/* extern struct sr_output_format output_analog_gnuplot; */
+/**
+ * @file
+ *
+ * Output file/data format handling.
+ */
+
+/**
+ * @defgroup grp_output Output formats
+ *
+ * Output file/data format handling.
+ *
+ * @{
+ */
+
+/** @cond PRIVATE */
+extern SR_PRIV struct sr_output_format output_text_bits;
+extern SR_PRIV struct sr_output_format output_text_hex;
+extern SR_PRIV struct sr_output_format output_text_ascii;
+extern SR_PRIV struct sr_output_format output_binary;
+extern SR_PRIV struct sr_output_format output_vcd;
+extern SR_PRIV struct sr_output_format output_ols;
+extern SR_PRIV struct sr_output_format output_gnuplot;
+extern SR_PRIV struct sr_output_format output_chronovu_la8;
+extern SR_PRIV struct sr_output_format output_csv;
+extern SR_PRIV struct sr_output_format output_analog;
+/* extern SR_PRIV struct sr_output_format output_analog_gnuplot; */
+/* @endcond */