Tcode ranges not working as expected

Hoping one of you can help me with the following question:

I created a role with a tcode range (although that's probably not a good practice) that has a from value S_ to SBC@. It seems to me that SA38 would be in the range (based on the ASCII table and a sorting of these values in Excel). However, users with that role cannot execute SA38.

Is there any detailed information out there as to how SAP works with ranges?

Thanks in advance!

Jose