Usage: see for example Template:Infobox element § Theoretical elements handling documentation

To reduce expensive edits (like checking #ifexists), some logic is derived by presumption (eg using |is-redirect=. And some is hardcoded, eg |isobox-exist=.

Per element:

{{Infobox element/period-8-elements/overview/check
 |Z         =
 |symbol    =
 |name      = <!-- lowercase -->
 |discovered=false
 |period    =
 |note      =
 |set-status= <!-- set ID like 'E119' -->
}}

Subtemplates:

Table is documentation only. Not for mainspace. Implemented in eg {{Infobox element}}, usually via |number= (=Z).