I’ve been reading the Keywords section of the rules (Sunday afternoon) and in the keyword ‘May’ gives us some interesting consequences.

If you replace the definition of ‘may’ into a sentence with the phrase ‘may not’ then you do not get ‘is not permitted to’, but instead you get ‘is permitted to not’. This difference is important, as the example below illustrates:

“You are not permitted to eat my ice-cream.”

or

“You are permitted to not eat my ice-cream.”

Now what we want with the keyword is to get the above result. The bottom one is what we have currently. As courteous as the bottom one is, it won’t stop you eating the ice-cream.

I therefore propose that we add the following Keyword to the Appendix:

May not
“Is not permitted to”

I think this is the simplest solution. This argument does not apply to the Keyword ‘can’ because ‘cannot’ is a separate word, and technically is not defined by the keyword ‘can’.