Translating this meaning into English:
There is a value that a computer user can set. Not setting the value is an invalid program state and should not be allowed. Setting and empty value is equally forbidden. If setting a value is done so:
value = "ExceptionalCoconut";
setting an empty value is done so:
value = "";
With the latter software command, an attempt to set the value is made but the actual value, between double quotes, is effectively empty. This should be disallowed.
Now on to the error message to display if either erroneous usage is attempted and my attempt at phrasing that in English:
valuecannot be null nor empty.
I chose this over:
valuecannot be null or empty.
Which one is correct — or or nor?