Regex help on non-capturing groups

Question

Must be a duplication but I can\'t seem to find it...

I am using a group to match a repeating sub-string. However, I do not want the group to be captured. This seems to

Answer 1

The reason this won't work is that when you write \1 you basically say "the content of the first group", which is of course undefined if the group is non-capturing.