Should this be only for implementations, or all built-in types and persistent objects?

In T289793#7320124, @Lindsaykwardell wrote:

Should this be only for implementations, or all built-in types and persistent objects?

This was specifically for built-in code implementations (i.e., Implementations which have their Z14K4 set), because we have nothing meaningful to render to the user, just an internal string token pointing to the code in the evaluation layer. It's not for all ZIDs < 10k. And yeah, it's irritating that we have used 'built-in' to mean both. :-(

Change 716043 had a related patch set uploaded (by Lindsay Wardell; author: Lindsay Wardell):

[mediawiki/extensions/WikiLambda@master] Display a message on Built-In Implementations

https://gerrit.wikimedia.org/r/716043

Change 716043 merged by jenkins-bot:

[mediawiki/extensions/WikiLambda@master] ZImplementation: Display a message on built-ins explaining why they're blank

https://gerrit.wikimedia.org/r/716043