Conventional IDE (or parallel ATA) controllers support two devices per controller; these are designated Master and Slave, and need to be configured as such with jumpers on the devices.
In later years, another option was available: the use of Cable Select. In this arrangement the drive was not jumpered as Master or Slave, but a third option that would allow the drive to select either option depending on its position on the IDE cable. I believe this was done by only connecting pin 28 to one of the two device connectors on a compatible IDE connector, the presence or absence of which would be detected by the device.
I can picture situations where the ability to have the drive configure itself based on the cable location would be useful, such as a machine with a number of removable drive bays. I never had occasion to use it myself (or at least never got it working), so continued to use the Master / Slave options until the advent of SATA devices.
My question is as follows:
When did IDE devices (and controllers/cables) supporting Cable Select become available?