@PinkLady4 - A cousin of mine worked in the supplier section of a retail value chain. She said the system is really quite complicated and it is changing all the time, partly due to globalization and the added competition.
I guess the main idea is that the parts of the retail chain must constantly share information so that shared goals are met, such as getting the product onto the shelves at the right time.
Each link needs to be able to look at and evaluate what is going on in every other link.
This is some general explanations for your questions. I really don't know how the specifics work. Anyone?