doc UPDATE libyang v3 transition
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+/**
+ * @page transition2_3 Transition Manual (2.x -> 3.0)
+ *
+ * [TOC]
+ *
+ * Non-backwards-compatible changes between libyang version 2 and 3 are rather minor and can be summarized as providing
+ * structured error information (instead of a single message), unifying **lyd_new_*()** function options, and some
+ * minor changes such as removing deprecated functions or making a few functions inlined. However, there is another
+ * large change that has not affected the API, specifically configuration system-ordered lists and leaf-lists are now
+ * ordered based on their keys/values, respectively. Except for moderately slower performance and negligible increased
+ * memory requirements, it should not affect existing applications (assuming they do not rely on the previous order of
+ * these instances).
+ *
+ * The complete generated list of changes (without any additional notes) can be found in
+ * <a href="../compat_report_2_3.html">the compatibility report</a>.
+ *
+ * @section transition2_3Logging Logging
+ *
+ * Except for some function adjustments, ::ly_err_item has been changed to provide every piece of error information in a
+ * separate member to allow for easier processing.
+ *
+ * Here is the overview of the changed / removed / added functions connected to logging.
+ *
+ * libyang 2.x | libyang 3.0 | Notes
+ * :-------------------------|:-------------------------------------|:-------------------------------------------------------
+ * ly_last_errmsg() | ::ly_last_logmsg() | Function renamed with the same functionality.
+ * ly_strerrcode() | ::ly_strerr() | Function renamed with the same functionality.
+ * ly_errcode() | - | Now requires ::ly_err_last() call.
+ * ly_errmsg() | - | ^
+ * ly_errpath() | - | ^
+ * ly_vecode() | - | ^
+ *
+ *
+ *
+ * @section transition2_3New Data Creation
+ *
+ * libyang 2.x | libyang 3.0 | Notes
+ * :-------------------------|:-------------------------------------|:-------------------------------------------------------
+ * lyd_find_xpath3() | ::lyd_find_xpath3() | Optional prefix data parameter added.
+ * lyd_new_path() | ::lyd_new_path() | All options now in a single bitmap parameter of @ref newvaloptions.
+ * lyd_new_any() | ::lyd_new_any() | ^
+ * lyd_new_list() | ::lyd_new_list() | ^
+ * lyd_new_list2() | ::lyd_new_list2() | ^
+ * lyd_new_list3() | ::lyd_new_list3() | ^
+ * lyd_new_meta() | ::lyd_new_meta() | ^
+ * lyd_new_meta2() | ::lyd_new_meta2() | ^
+ * lyd_new_term() | ::lyd_new_term() | ^
+ * lyd_new_list3_bin() | ::lyd_new_list3() | Functionality now merged into the single function.
+ * lyd_new_list3_canon() | ^ | ^
+ * lyd_new_list_bin() | ::lyd_new_list() | Functionality now merged into the single function.
+ * lyd_new_list_canon() | ^ | ^
+ * lyd_new_term_canon() | ::lyd_new_term() | Functionality now merged into the single function.
+ *
+ *
+ *
+ * @section transition2_3Minor Other Minor Changes
+ *
+ * Except for the function changes below, ::lysc_type now has a copy of the typedef name, if applicable. There
+ * are use-cases when this information is needed even in the compiled schema tree such as checking the real type of
+ * a union value.
+ *
+ * libyang 2.x | libyang 3.0 | Notes
+ * :-------------------------|:-------------------------------------|:-------------------------------------------------------
+ * lyd_child() | ::lyd_child() | Now an inlined function for better performance.
+ * lyd_get_value() | ::lyd_get_value() | ^
+ * lyd_parent() | ::lyd_parent() | ^
+ * lyd_find_xpath4() | ::lyd_find_xpath3() | Previous lyd_find_xpath3 was removed to reduce symbols.
+ * lyd_target() | - | Deprecated.
+ * ly_ctx_reset_latests() | - | ^
+ *
+ */