Amusingly in the UNIVAC FIELDDATA character set. The @ had the value zero
(and was called the master space).
It's sort of like making NUL the command character :)
Amusingly UNIVAC had their own punched card format (same size card, which
was by the way, the size of a dollar bill in Hollerith's day) but used two
banks of 45 round holes for 90 columns.
-Ron "I had a cat named @FURPUR" Natalie