NCD X Terminals

Greetings! I am trying to finish documenting NCD keyboards and there's one area that has proven to be quite elusive... I don't expect to uncover any/many answers here, either -- but, it's worth a shot... Has anyone ever *seen* a "secure keyboard" for an NCD? Does it *look* the same as any other keyboard? If so, *which*? Or, was this an option that could be incorporated into *any* of the standard keyboards? It is my understanding that there were no other "magic keys" *added* to the keyboard to get these features; is that true? What was the procedure used to secure and unsecure the NCD? Presumably, the keyboard identified itself to the terminal in such a way that the terminal would add extra "security" options to the various menus. Were these user-visbile changes limited to the boot monitor? Or, were there consequences evident in NCDware? Are there any markings on the keyboard that identify it as such (e.g., a different model number, etc.)? Photos would be *excellent*! Extra credit question: what is the keyboard code that it delivers to the terminal to identify itself? Thanks! --don