As with modifiers, a group selector can be associated with a key, but can also be latched or locked.
2.
TXE6 was an electronic common control exchange that was designed to extend Strowger exchanges, and known as the Electronic Reed Selector System or Reed Group Selector ( RGS ).
3.
The translated digits were sent to the code selectors, and then the four numeric digits were sent to three switching stages in the terminating exchange ( two group selectors and a final selector ).