Devices that always spin at the same rate are called CAV (Constant Angular Velocity) drives.

Devices that maintain a fixed linear velocity are called CLV (Constant Linear Velocity) drives.

Devices that switch from CAV to CLV when the maximum speed is reached are called PCAV (Partial Constant Angular Velocity) drives. Most of the recent high-speed CD-ROM drives are PCAV.

Devices that are CLV, but use different speeds on different parts ("zones") of the disc, are called ZCLV. Most CD recorders use CLV while writing, but some (e.g. 20x and higher) use PCAV or ZCLV.