Was just reading in the Uncrackable Password thread and started to enter information that was more suited to this forum so am entering it here. So would anyone who remembers this feature please respond with the system that it worked on.
Some time ago (DOS period maybe) one could hold the Alt key down while holding the Sys req key while entering numbers and a space would be filled with a character but the character was not displayed. ex. hold the Sys Rq key and Alt key and press 0150. This would display a blank space that would require someone trying to fill in the password to enter a short dash using the unicode ascii character set.
As I was typing this it dawned on me that it was so long ago that it might have been in an old CPM system such as Interact Model 1 or a KIM which wouldn't apply to this Uncrackable Password forum.