Do you mean the first three characters could either be letters or numbers, like A1B12345 or ABC12345, or do you mean there is a number and semicolon three times such as A1;B2;C3;12345 ?

Also clarify how you managed to access the scanner's history. Is there some vendor software that shows you this (I assume you're using Windows), or does the scanner have some kind of removeable storage card that you can insert in a computer to read the history?