CF-xxx vs. C-Fxxx

"Dylan Smith" wrote in message
...
On 2005-10-06, Steven P. McNicoll wrote:

When are letters numbers?


Generally in any base base 10. Base 36 for instance uses the digits 0
to Z - so every letter of the alphabet is a number.

Hex is very common (0-F), but we do have one system that uses base 36.
Base 64 encoding is also common (in which case 'a' is a different number
to 'A')


In the base that Canada uses for aircraft registration, when are letters
numbers?