Currently still making the big leap from 9.10 karmic to 12.04.1 LTS, ah and now 14.04. 18.04...
My *X socialization was (in that order): HP-UX, Aegis/Domain-OS/Domain-IX, Digital, AIX, Slackware, Redhat, Ubuntu. SUN only marginally.
When I hear
TL;DR, I still think "to left", "define region".