# Mathematical description of an identifier which consists of text and numbers [closed]

in my code I use an artificial identifier of the form UIxxx where xxx is in the range of 1 to 999. In my assay, where I describe this unique identifier I am not sure how to mathematically describe it. Can I say something like:

UIxxx, where 1 < x < N, with N max = 999;

OR:

UIx, where x is element of N={1, 999}

-

## closed as too localized by rschwieb, Paul, Davide Giraudo, Thomas, ArkamisMar 13 '13 at 14:21

This question is unlikely to help any future visitors; it is only relevant to a small geographic area, a specific moment in time, or an extraordinarily narrow situation that is not generally applicable to the worldwide audience of the internet. For help making this question more broadly applicable, visit the help center.If this question can be reworded to fit the rules in the help center, please edit the question.

I would go with the second suggestion. The first one might imply that it would be possible to have UI999999999, if x=999. –  sonystarmap Mar 13 '13 at 11:46
In the second suggestion, you should still say $1\leq x\leq 999$ - what you have written literally means that $x$ is either $1$ or $999$. –  Matthew Pressland Mar 13 '13 at 11:58
So, would it be correct to write: An identifier of the form UIx, where x is element of N = {1, 2, 3, ..., 999}. –  user969113 Mar 13 '13 at 12:48
@user969113 Yes, but I think Christian's is clearer, particularly as it doesn't introduce unnecessary notation. (For example, you don't gain anything from calling that set $N$). –  Matthew Pressland Mar 13 '13 at 13:10
Ok, thanks for confirming this and yeah I guess you are right that a mathematical definition for this might be over the top and it is better to just use words as Christian did. –  user969113 Mar 13 '13 at 13:27