Multi-level Custom Fields

I found a single email thread regarding multi-level ticket classification (
Carbon60: Cloud Consulting - Services and Solutions). Unfortunately, it
doesn’t go into any detail. It is a few years old and refers to 3.8.6. Does
the functionality to implement these custom fields still exist under 4.2?
Where can I find some documentation for it?

-Mathew

“When you do things right, people won’t be sure you’ve done anything at
all.” - God; Futurama

“We’ll get along much better once you accept that you’re wrong and neither
am I.” - Me