> How can this help to add an attribute to elements containing the
> symbols?

It can't. (one trick of answering lots of questions is not to read the
whole question before answering, but sometimes you get it wrong.....)
I cut that character map out of one of my own stylesheets so I had it in
mind....

It may be useful but doesn't really help the OP (the first part of my
answer was on topic though I hope:-(

David