In ,
Priti had this to say:

My reply is at the bottom of your sent message:

I have been trying to use the product key to register my software,
but its saying "you have not entered the valid product key." I'm so
frustrated, I don't know what to do.

I am not sure if this helps but I just went through a huge stack of
Microsoft Keys (all handily printed out for me too) and I don't see any
instances of a zero nor of the letter "O" anywhere. I think that this was
disallowed because it led to confusion. So if it looked like a 0 or a O it
was probably the Q that sf mentioned. I also don't see any L, 1, or I
listed. Somewhere there's gotta be a list of these things. g As they are
always in capital letters (you should hit the caps lock before entering the
key as it will make it easier to spot typographical errors) I am not sure
why they didn't go ahead and use the L or I but I suppose it's simpler
without them.

Galen
--

"But there are always some lunatics about. It would be a dull world
without them."

Sherlock Holmes