types FEATURE partial support of instance-identifier data type values

- predicates are not yet supported
diff --git a/src/tree_data.h b/src/tree_data.h
index 0e1626a..ec23aac 100644
--- a/src/tree_data.h
+++ b/src/tree_data.h
@@ -177,6 +177,10 @@
         struct lysc_type_bitenum_item *enum_item;  /**< pointer to the definition of the enumeration value */
         struct lysc_type_bitenum_item **bits_items; /**< list of set pointers to the specification of the set bits ([sized array](@ref sizedarrays)) */
         struct lysc_ident *ident;    /**< pointer to the schema definition of the identityref value */
+        struct lyd_value_prefix {
+            const char *prefix;           /**< prefix string used in the canonized string to identify the mod of the YANG schema */
+            const struct lys_module *mod; /**< YANG schema module identified by the prefix string */
+        } *prefixes;                 /**< list of mappings between prefix in canonized value to a YANG schema ([sized array](@ref sizedarrays)) */
         int8_t int8;                 /**< 8-bit signed integer */
         int16_t int16;               /**< 16-bit signed integer */
         int32_t int32;               /**< 32-bit signed integer */