My solution is just to add the four digit article code to the bottom of the article content, although not ideal, it works and the search function finds it easily.

I've tried creating unique tags and categories for the articles such as a four digit number, but when I enter that into the search function it does not find the article with the associated tag, even though I have tagged an article with the tag or category.

What am I missing, can this be done? Allowing the user to search for a word results in too many articles being found because the search function finds those words in multiple articles....