Field Change Function on Transaction Form

Hi all,

I have a Field Change function operating on an Expense Report form.  This function checks to see if the user has changed the value of a number of Expense column fields, and performs some processing / validation depending on the column field changed.  One such process is to set the Tax Code based on the user selecting a Currency (when 'Use Multi Currency' is ticked).

I am finding that the function is correctly triggered when the Currency is changed, and also correctly sets the Tax Code field, however, based on the Execution Log, I can see that it runs the passage of code for the Currency Field Change twice.  That is, it appears that when the user changes the Currency, my 'if name == currency' condition triggers, then based on certain rules, I set the Tax Code field, which then triggers the Field Change function again (which it should as a field has indeed just been changed - the Tax Code).  This Field Change performs