Crystal Help - AR Invoice design

Forum,

I am trying to design an AR Invoice layout in Crystal 2008 and would like to suppress the item code from the print preview and instead show the lines on the AR Invoice which have a row type of 'T' with it's full description. I suspect this will require a formula field as it is a variable and isn't available for selection from the list of standard fields within INV1.

Any help or assistance would be greatly received!

Thanks in advance.

Sarah