How can I extend org symbols table?

Question

I use org UTF8 character substitution all the time, for example to go from \beta to β (enabled with the org-pretty-entities variable).

However some standard symbols are missing and I'd like to add them manually. For example, I'd like to map \| to ‖. How can I do that?

Reference: Org Symbols Table

Answer 1

M-x customize-group RET org-entities, then fill the form under Org Entities User. The name field is the one which will enable the transformation.

I set name: Norm so that \Norm transforms to ‖. I couldn't get it to work for \| however.