# 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}

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

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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 $999$. –  Matt 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 $N$). –  Matt 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