What is not possible via JSL?

[#1]

https://community.jmp.com/t5/Discussions/Is-it-possible-to-show-excluded-row-values-on-chart-via-JSL... 

Where are the limits? 

I mean:

- where is the the GUI/mouse user ahead of his JSL colleague?
- where is a hard wall for any Jmp user?

[#2]

#2: it is not possible to create a custom function with a column reference *)

(Jmp v17.2)

*) one  which could be used in the right click new formula column menu:

Custom Function - how to reference the column

actually, a similar question was asked some while ago by @jthi  together with some other questions:
Creating statistical custom (formula) function which has byVar and  @ih shows that with some workaround it's possible to solve the first riddle: create a custom function with a column reference

But the workaround prevents it from being usable in the right click new formula column menu

edit:
same question some years ago:
Column reference in custom function 

[#3]

This is a good idea. Rather than fixed the name as control limit. Just name it with "Customized Limits". Sometimes user may want to add alarm before control limits.

Thanks for sharing. I will upvote the above wishlist first