-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;
+/**
+ * @file
+ *
+ * Output file/data format handling.
+ */
+
+/**
+ * @defgroup grp_output Output formats
+ *
+ * Output file/data format handling.
+ *
+ * libsigrok supports several output (file) formats, e.g. binary, VCD,
+ * gnuplot, and so on. It provides an output API that frontends can use.
+ * New output formats can be added/implemented in libsigrok without having
+ * to change the frontends at all.
+ *
+ * All output modules are fed data in a stream. Devices that can stream data
+ * into libsigrok, instead of storing and then transferring the whole buffer,
+ * can thus generate output live.
+ *
+ * Output modules generate a newly allocated GString. The caller is then
+ * expected to free this with g_string_free() when finished with it.
+ *
+ * @{
+ */
+
+/** @cond PRIVATE */
+extern SR_PRIV struct sr_output_format output_bits;
+extern SR_PRIV struct sr_output_format output_hex;
+extern SR_PRIV struct sr_output_format output_ascii;