There's a longer story, but I assure you the change is on purpose. I think at some point it made more sense to refer to the triggers by numbers for two reasons:
1: Triggers can more obviously be assigned programmatically. (eg.
L 1 4 : TR.PULSE I)
2: This encourages the use of variables
D as general purpose variables.
Of course all code is backward compatible as the 4 variables have always just been normal variables which default to 1-4 respectively.
I really like the faint grey lines! Think @tehn did a great job of minimally differentiating the groups of jacks there.