Rob
Ansys Employee

We (staff) can only refer you to the documentation, which also gives some further clues   https://ansyshelp.ansys.com/account/secured?returnurl=/Views/Secured/corp/v222/en/flu_udf/flu_udf_DataAccessMacros.html?q=header%20les  If there are data macros in Fluent header files I wonder what else could be in those files/folder....