Registration IP In Backend ACP

What code in what window?

Supply your custom html and substitutions to the Description parameter. Whatever you supply there will display as the fields value.

How do I do that?

How do you do what? You add whatever HTML and/or substitutions you want to the Description parameter after setting the fields type to Custom HTML. Your first post already has the substitution to output IP Address.

www.joomlapolis.com/forum/149-usage/239591-registration-ip-in-backend-acp?limitstart=0#306559

Excuse me, but to "delimiter " was more explicit. Now that I found, it is not any more a problem. But very disconcerting in evolution of site. We have an impression that a parametre disappeared. Put in parentheses "Delimiter" in the description of the type of field. (Translation French ==> English with PROMP 19 MASTER)

Delimiter field was renamed to Custom HTML field. Sorry, I don't understand what your issue is. Of course we're still going to have some forum posts referencing the delimiter field (which again is just the Custom HTML field) as that's what it previously was named. The delimiter field wasn't a delimiter field when it became capable of outputting custom HTML and thus it was renamed something more appropriate to its usage. If you don't like it being renamed use language overrides to change it to display whatever you want for its field type name.