strBuild is the concateneated string so far.
strItem is the string to add and could be blank or a constant "File Not Required"
If the string is blank, null or not required then the original strBuild string is returned otherwise if strbuild is not blank a comma is added in preparation for adding the stritem then the string is returned as the function result.
function retFileNames(strBuild, strItem)
if stritem = "File Not Required" or stritem = "" or stritem = "None" then
retFileNames = strbuild
if strbuild = "" then
retFileNames = stritem
retFileNames = strBuild & "," & stritem