This article is intended for someone who already has experience progamming Yahoo Store and is familiar with Yahoo's documentation and/or programming their shopping cart. Yahoo store has traditionally developed their own custom shopping cart language that allows web developers to work with.
The problem has always been that if you have a lot of items in the Yahoo's catalog manager, you want to make them dynamic. In order to do dynamic programming one usually uses a programming language like PHP and a database like MYSQL.
Well, here is the problem, Yahoo technical support does not support PHP/MYSQL since there are lot of web developers with a range of different skill levels. They just support Yahoo store backend core functionality. If you need a special customized shopping cart and Yahoo's tools aren't enough for you, then you are on your own.