It is common to use the last selector to prevent family members from playing each other. All the possible codes are shown in the dropdown list.
You can also create one of 10 top groups with a code like (d:) where d is one of the digits (0 - 9). GoDraw was automatically completing a typed 1 to 1: and if you then press Enter the register edit is happily accepted, but you have created a supergroup and not a special group. The auto complete has been switched off and you get a message reminding you what your options are. You cannot continue until you close the message, so you cannot inadvertently create a top group when you meant to create a special group.You can also use the menu Tools->Groups to create any group of your choice. Here you can easily select players and the super/special group codes cannot be confused.