When you define a new channel, it will be added to the collection of channels and each such channel will be allocated an index number. The index of any given channel can change during its lifetime and is not persistent. The first channel will have an index 0, the second will have an index 1 and so on. If first channel is removed (with index 0), then all the remaining channels have their index property decremented by 1.
New channels are always added at the end of collection.
If you want an index that you can use throughout the duration of a channel's lifetime, use the
Name property.