I don't think it has one. The Ferrari 4000 service manual doesn't say a word about "trusted" computing either.
Not that I miss it though. While the TPM chip is not evil on itself, the features the OS and/or BIOS may enable based on it are terrifying ("secure" boot, where only an authorized OS can run on a computer, uses for DRM, etc.) Richard Stallman has written a nice article about what trusted computing really means for users http://www.gnu.org/philosophy/can-you-trust.html