data tree DOC doxygen update
diff --git a/src/tree_data.h b/src/tree_data.h
index ce96f0b..e2ab7d2 100644
--- a/src/tree_data.h
+++ b/src/tree_data.h
@@ -491,8 +491,13 @@
* @brief Search in the given data for instances of nodes matching the provided XPath expression.
*
* The \p data is used to find the data root and function then searches in the whole tree and all sibling trees.
+ * The XPath expression is evaluated on data -> skip all non-data nodes (input, output, choice, case).
*
- * @param[in] data A node in the data tree considered the context node. If the node is a configuration one,
+ * Expr examples:
+ * "/ietf-yang-library:modules-state/module[name = 'ietf-yang-library']/namespace"
+ * "/ietf-netconf:get-config/source"
+ *
+ * @param[in] data Node in the data tree considered the context node. If the node is a configuration one,
* any state nodes in its tree are not accessible!
* @param[in] expr XPath expression filtering the matching nodes.
* @return Set of found data nodes (use dset member of ::ly_set). If no nodes are matching \p expr or the result