This function takes a series of strings as arguments. It will test if each one is the null string (""). If not, it will return that string and stop. If it is null, it will continue on to the next one, and test that. This will continue until either one of the strings is non-null, or it reaches the last argument. Arguments after that are not evaluated. Usage: @strcheck("", "", "a") @strcheck(@getfield("123", "va"), @getfield("123", "vb"), "Not found.")