From the cme site (
https://www.cmegroup.com/trading/price-limits.html#equityIndex):
View attachment 241276
I like that it shows all of the limits, and it makes it clear that there's a High Limit only during overnight hours. From higher up on that page, the bullets show this:
View attachment 241278
So it seems that at the time you took your screenshot (with a last-updated time of 16:40 CT on Friday Oct 9), the table SHOULD HAVE SHOWN "Undefined". Just kidding, but note that the bullets don't mention what the limits are between 16:00 and 17:00 CT on Fridays (on Mon-Thurs that hour is "Daily Maintenance"). So it seems that the table considers that hour to still be regular trading hours, which have no High limit.
Here's the current output of that same table:
View attachment 241277
Right now trading is closed but overnight hours begins in about a half hour, so there're both High and Low limits.