diff --git a/include/coap/resource.h b/include/coap/resource.h
index 9c7b45ce..dbb19a8d 100644
--- a/include/coap/resource.h
+++ b/include/coap/resource.h
@@ -57,8 +57,19 @@ typedef struct coap_attr_t {
   int flags;
 } coap_attr_t;
 
+/** The URI passed to coap_resource_init() is free'd by coap_delete_resource(). */
 #define COAP_RESOURCE_FLAGS_RELEASE_URI 0x1
+
+/**
+ * Notifications will be sent non-confirmable by default. RFC 7641 Section 4.5
+ * https://tools.ietf.org/html/rfc7641#section-4.5
+ */
 #define COAP_RESOURCE_FLAGS_NOTIFY_NON  0x0
+
+/**
+ * Notifications will be sent confirmable by default. RFC 7641 Section 4.5
+ * https://tools.ietf.org/html/rfc7641#section-4.5
+ */
 #define COAP_RESOURCE_FLAGS_NOTIFY_CON  0x2
 
 typedef struct coap_resource_t {