internal string BuildScriptAttribute (string name, string tail)
{
AttributeCollection attrs = Attributes;
string attr = attrs [name];
if (attr == null || attr.Length == 0)
return tail;
if (attr [attr.Length - 1] == ';')
attr = attr.TrimEnd (_script_trim_chars);
attr = String.Concat (attr, ";", tail);
attrs.Remove (name);
return attr;
}