There was no such thing in the world before you guys made it up, right?
Wrong. You can always send your coins to "<messageHash> OP_DROP <pubkey> OP_CHECKSIG" and spend them.
Really?

Just because we have scripts that USE Digital Signature schemes, then we have a Programmable Digital Signature system? Are you kidding or what?
Before rushing to the keyboard, always do your homework: Google it! Programmable Digital Signature System.
Done? As I said, and you quoted, there is no such thing in the world, Right?