Yes, but it’s also part of the same consolidation I mentioned earlier. sr? was the SCSI CD-ROM interface. Now it covers all CD-ROM-like devices.
I’m not sure what it stands for, but, if I had to guess, I’d say SCSI ROM, since all the devices it took were basically some type of Read Only Memory.
If you didn’t guess, hd stands for hard drive, while sd stands for SCSI drive. While it would make more sense to consolidate under hd if they’d done it all at once, as indicated by Fubaya, it took them a while for the new SATA/PATA (sd) driver to be good enough to completely remove the old IDE (hd) driver.