Conservative extension

Okay kiddo, sometimes when people talk about things, they want to make sure they don't change the meaning of what was said before. That's called being "conservative".

Now imagine you have two different sets of rules or information. You want to see if one set is just like the other set, but with some extra rules added onto it. That's called extending one set to another.

So a "conservative extension" is when you add new rules or information onto one set, but you make sure those new things don't change the meaning of the original set. It's like you're being careful and keeping everything the same, just with some new additions.