The 4C Entity's 2000–2001 CPRM proposal for ATA hard drives was designed to bind protected content to a specific physical drive via a GUID-based mechanism

The 4C Entity — a consortium of IBM, Intel, Panasonic (Matsushita), and Toshiba formed in 1999 "to address the interoperability challenge of sharing premium content" (4C Entity white paper, Tier 1, sha256 ce2baad3...) — proposed extending the T13 AT Attachment (ATA/IDE) command set so compliant hard drives could enforce CPRM (Content Protection for Recordable Media). Contemporaneous coverage describes the core mechanism as a Global Unique Identifier (GUID) scheme meant to tether encrypted content and its decryption keys to one specific physical drive, rather than allowing system-independent key exchange — with enforcement reportedly split between the drive (honoring lock/passcode commands) and host software (the OS or application layer holding the release key). This would have been the first attempt to embed copy-prevention logic directly into a mainstream PC storage-interface standard rather than into removable media alone; the same underlying CPRM technology also shipped in SD cards — where it was part of the SD specification from the format's launch (mandatory until SD spec 6.10, 2018, per the SD Association's content-protection page), with a separate "SD-Separate Delivery" (SD-SD) part extending the SD CPRM book around 2007.

The mechanism description above rests entirely on EFF and Register coverage obtained through a fetch-and-summarize tool rather than a direct read of the actual T13 filings (document series e00148r0/r1/r2), which sit behind a members-only login at t13.org. Per the vault's sourcing floor, a technical-mechanism claim needs Tier 1–2 sourcing read directly, not summarized, so this stays [unverified-mechanism — needs primary], routed to question-verify-cprm-t13-rejection-4c-entity-eff. See also claim-ibm-withdrew-2001-cprm-ata-proposal-resubmitted-as-generic-functionality and claim-t13-rejected-generic-functionality-proposal-april-2001-supermajority-rule for the fight this proposal triggered, and claim-davidoff-2001-opposed-cprm-drm for the vault's original, thinner mention of this same episode.