CPRM means Content Protection for Recordable Media
CPRM is a form of Digital Rights Management (DRM). It is a mechanism that can control the copying, deletion and moving of digital content on a device such as a personal computer or digital player. It uses a renewable cryptographic method to protect digital content when recorded on physical media such as DVD media or Flash memory.
In 2001, a proposal to include CRPM on ATA hard drives was abandoned due to opposition. CPRM is in use in the Secure Digital Card flash memory format. The use of CPRM in the format is not mandatory however so users are free to copy digital content to and from other devices.
Form a further example, the DVD-RAM format has CPRM support designed into it's specification so in Japan it can be used to record copy guarded digital broadcasts whereas other rewritable media doesn't support CPRM.