diff --git a/include/proto/trace.h b/include/proto/trace.h
index 5df7107..726fefd 100644
--- a/include/proto/trace.h
+++ b/include/proto/trace.h
@@ -55,8 +55,8 @@
 #define TRACE_USER(msg, mask, ...)			\
 	trace(TRACE_LEVEL_USER,      (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
-#define TRACE_PAYLOAD(msg, mask, ...)  \
-	trace(TRACE_LEVEL_PAYLOAD,   (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
+#define TRACE_DATA(msg, mask, ...)  \
+	trace(TRACE_LEVEL_DATA,   (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
 
 #define TRACE_PROTO(msg, mask, ...)    \
 	trace(TRACE_LEVEL_PROTO,     (mask), TRACE_SOURCE, ist(TRC_LOC), TRC_5ARGS(__VA_ARGS__,,,,,), ist(msg))
diff --git a/include/types/trace.h b/include/types/trace.h
index b3f418f..03eb7db 100644
--- a/include/types/trace.h
+++ b/include/types/trace.h
@@ -78,12 +78,15 @@
 	TRACE_STATE_RUNNING,      // waiting for the stop or pause conditions
 };
 
+/* trace levels, from least detailed to most detailed. Traces emitted at a
+ * lower level are always reported at higher levels.
+ */
 enum trace_level {
 	TRACE_LEVEL_USER = 0,     // info useful to the end user
-	TRACE_LEVEL_PAYLOAD,      // add info relevant to the payload
-	TRACE_LEVEL_PROTO,        // add info relevant to the protocol
-	TRACE_LEVEL_STATE,        // add info relevant to the state machine
-	TRACE_LEVEL_DEVELOPER,    // add info useful only to the developer
+	TRACE_LEVEL_PROTO,        // also report protocol-level updates
+	TRACE_LEVEL_STATE,        // also report state changes
+	TRACE_LEVEL_DATA,         // also report data exchanges
+	TRACE_LEVEL_DEVELOPER,    // functions entry/exit and any other developer info
 };
 
 enum trace_lockon {