>>>It's really unfortunate that some things end up becoming a debate. I prefer science. There is plenty of science involved in reading levels of text. There is Flesch-Kincaid grade level scoring built into MS Word.
>>>
>>>"The amount must be greater than or equal to zero." Reading level 4.8
>>>
>>>"The amount must not be negative." Reading level 7.6
>>>
>>>Clearly the second sentence is for a more sophisticated audience by almost 3 grade levels.
>>
>>I think most of our users will at least have high school diploma, so they'll understand what negative means :)
>
>I certainly hope that the person setting credit limits understands the difference between positive and negative numbers.

Not necessarily, they only know the difference between credit and debit. To them a negative credit means a debit, and vice versa.