If you only need to store 0 and 1, you can use setbit/getbit expressions. There was a post about them just today:
https://www.construct.net/en/forum/construct-3/how-do-i-8/someone-explain-setbit-164563
No, this time I need to store different values (4 , 7 , 13 etc), or even strings. I saw your answer about setbit, as I understood it pretty much works like a lot of independent boolean switches. That's useful, but not in that case. I could use RegEx, but I think there is a much more simple way to implement it, that I just can't see