Another patent misconception, from what I understand, is that an unenforced patent becomes invalid. It is said that PKP is "forced" to go after PGP because if they don't their patent will lose its force. Several days ago Tom Morrow on the Extropians list said that this doctrine applies to trademarks but not to patents. Patents have a fixed 17 year lifetime and failure to enforce against one user does not preclude the patent owner from enforcing against another. The folklore about the loss of intellectual property rights that we are all familiar with (aspirin, zippers, etc.) are all cases of trademark losses. Tom is a law student, not a lawyer; also, I am a few days behind on my Extropians reading so I don't know whether any follow-ups or corrections were posted since his message. But this principle seems to be in accordance with what was posted here about selective enforcement of patents. If this is in fact how patents behave, it is one less justification for PKP's heavy-handed enforcement efforts against PGP. It means that PKP could choose not to enforce against PGP (or any other freeware program) without losing any rights to enforce against others. It would be interesting to hear an authoritative opinion on this from a lawyer. Hal