[RTTY] "Slashed" Zeros vs. the number "Zero"

[Russmill47 at aol.com]

When did things change?  I'm just getting back to RTTY after a slight  break 
in service of 30 years.  My RTTY documentation shows that all Amateur  
Teletype equipment is set up with slash 0 for the number zero.  This was to  
differentiate from the letter 0.  
 
73,
 
Russ 
WA3FRP