Timing when ExcelFunction is called.

When we using UDF function (I mean function which has ExcelFunction annotation of exceldna), I thought that all UDF functions of sheet are called automatically when row or column of sheer is deleted or filter applying for items is changed.
But as my observation now, it seems to be called also when we even type any character in the cell after we register ExcelDnaXll64 (only on first time after registration)
So we need to know the cases which this all UDF functions of sheet are called for proper handling.
Thank you.