diff --git a/apps/backend/backend_plugin.c b/apps/backend/backend_plugin.c
index 7d6ab008..e02270c7 100644
--- a/apps/backend/backend_plugin.c
+++ b/apps/backend/backend_plugin.c
@@ -166,13 +166,24 @@ clixon_plugin_daemon_all(clicon_handle h)
 }
 
 /*! Call single backend statedata callback
+ *
+ * Create an xml state tree (xret) for one callback only on the form:
+ *   <config>...</config>,
+ * call a user supplied function (ca_statedata) which can do two things:
+ *  - Fill in state XML in the tree and return 0
+ *  - Call cli_error() and return -1
+ * In the former case, this function returns the state XML tree to the caller (which 
+ * typically merges the tree with other state trees).
+ * In the latter error case, this function returns 0 (invalid) to the caller with no tree
+ * If a fatal error occurs in this function, -1 is returned.
+ *
  * @param[in]  cp      Plugin handle
  * @param[in]  h       clicon handle
  * @param[in]  xpath   String with XPATH syntax. or NULL for all
- * @retval    -1       Error
- * @retval     0       Statedata callback failed
- * @retval     1       OK if callback found (and called) xp is set, otherwise xp is not set
- * @note xtop can be replaced
+ * @param[out] xret    If retval=1, state tree created and returned: <config>...
+ * @retval    -1       Fatal error
+ * @retval     0       Statedata callback failed. no XML tree returned
+ * @retval     1       OK if callback found (and called) xret is set
  */
 static int
 clixon_plugin_statedata_one(clixon_plugin  *cp,
@@ -194,6 +205,7 @@ clixon_plugin_statedata_one(clixon_plugin  *cp,
 			   __FUNCTION__, cp->cp_name);
 	    goto fail;  /* Dont quit here on user callbacks */
 	}
+
     }
     if (xp && x)
 	*xp = x;
@@ -212,11 +224,11 @@ clixon_plugin_statedata_one(clixon_plugin  *cp,
  * @param[in]     yspec   Yang spec
  * @param[in]     nsc     Namespace context
  * @param[in]     xpath   String with XPATH syntax. or NULL for all
- * @param[in,out] xtop    State XML tree is merged with existing tree.
+ * @param[in,out] xret    State XML tree is merged with existing tree.
  * @retval       -1       Error
  * @retval        0       Statedata callback failed (xret set with netconf-error)
  * @retval        1       OK
- * @note xtop can be replaced
+ * @note xret can be replaced in this function
  */
 int
 clixon_plugin_statedata_all(clicon_handle    h,
diff --git a/lib/src/clixon_xpath.c b/lib/src/clixon_xpath.c
index 3959a446..434c3125 100644
--- a/lib/src/clixon_xpath.c
+++ b/lib/src/clixon_xpath.c
@@ -210,7 +210,7 @@ xpath_tree_print_cb(cbuf       *cb,
  * @see xpath_tree2str
  */
 int
-xpath_tree_print(FILE  *f, 
+xpath_tree_print(FILE       *f, 
 		 xpath_tree *xs)
 {
     int   retval = -1;
diff --git a/lib/src/clixon_xpath_eval.h b/lib/src/clixon_xpath_eval.h
index d8c9b296..28ab024a 100644
--- a/lib/src/clixon_xpath_eval.h
+++ b/lib/src/clixon_xpath_eval.h
@@ -2,7 +2,8 @@
  *
   ***** BEGIN LICENSE BLOCK *****
  
-  Copyright (C) 2009-2019 Olof Hagsand and Benny Holmgren
+  Copyright (C) 2009-2019 Olof Hagsandc
+  Copyright (C) 2020 Olof Hagsand and Rubicon Communications, LLC(Netgate)
 
   This file is part of CLIXON.