Sales order: Hide a message in packing slip

Hi all, I'm newbie in dynamic AX, and I'm having a question.

On packing slip we showing a message in the footer by calling the display method:

display FormLetterTxt Txt()
{
 return FormLetterRemarks.Txt;

}

I need hide this message in case when we do an international process. As a filter I can use  ItemID(where all international items are starting with prefix: INT)

If I could use simple logic:

display FormLetterTxt Txt()

{
 str name;
 str res;
;
 name = 'INT-WX350';
 res = substr(name,1,3);

   if(res == 'INT')
    {
      return ' ';
    }
     else
     {
        return FormLetterRemarks.Txt;
      }
}

Any thoughts?

Thanks much for the help!

Alex