diff --git a/src/gb/gprs_ns2_internal.h b/src/gb/gprs_ns2_internal.h
index 29717c6..b4d0a0d 100644
--- a/src/gb/gprs_ns2_internal.h
+++ b/src/gb/gprs_ns2_internal.h
@@ -220,6 +220,7 @@
 	void *priv;
 
 	bool nsvci_is_valid;
+	/*! should this NS-VC only be used for SNS-SIZE and SNS-CONFIG? */
 	bool sns_only;
 
 	struct rate_ctr_group *ctrg;