Thank you @neauoire for your reply!
The way the language has evolved is through community feedback, people finding ways to replicate an operator simply by combining two others, or recycling rarely used operators in more useful things. The operators have not changed in a few months now, it’s likely to stay like this.
Cool. I actually like the current set of operators.
Use something like 1x0 to create reset buttons for your iterator and bang it to reset the counter
Your example works, but I think my problem is a bit different. I actually want to reset the iterator to 0, but only when I reset the frame with Ctrl+Shift+R. Here’s another example without an iterator to demonstrate my problem:
.aV0....
........
........
..Va....
..0Mz.D.
50X0....
......z0
......0.
In this example, I manually change aV0 to aV1. The value at the bottom will slowly increase to z. I use this value, to set the velocity of a midi note, which will slowly blend in over time. When I want to fade out the midi note, I set aV1 to aV0.
The thing is, when I’m extending the patterns I often reset the frame with Ctrl+Shift+R. And before I start again I need to make sure that I set the variable a to zero and also the bottom value below the z.
This is a simplified example. But imagine a project, where you have many variables to steer the music and when I reset the frame, I have to zero out all variables and make sure that all values, which are influenced by the variable, are reset too.
In this case, I would need an operator which only runs once when I open the project or when I reset the frame.
Mind you, it’s not that important. I don’t think there’s a solution and I don’t expect one. I guess, this is something I need to get used to or maybe I’m approaching this problem from the wrong side… 
The C version is meant to be very simple and lean, a lot of the decisions like not including OSC and complex midi operation are made to keep the codebase simple.
Alright! I can understand that 
We(Hundred Rabbits) are progressively moving away from Github entirely.
Fair enough. 