all Tstring, Tlist, Tcontainer, Tmemo.lines,... and many more objects/class start with index 0 and run to (Txx.count-1). That makes it consistent across predefined objects/classes so you do not need to be an expert to use them. learn the basics of array handling for one and your good for the others.
I look for a .count and .items[] elements in any class/object I have not used before and if found, I know the basic indexes needed to step though the list.