I'm reading the iTunes Connect Developer Guide as I'm trying to add a new application to iTunes Connect.
I'm a bit confused about the SKU number which I should provide. On page 81 in the above developer guide they provide an example of their data for their application Orange Ball.
They have chosen Orange_Ball_01 for the SKU Number. What is the 01 indicating - that it is version 1? Why use underscore? Why not just type “OrangeBall”, if that SKU is not used?
You are able to choose one that you like, but it has to be unique.
Every time I have to enter the SKU I use the App identifier (e.g. de.mycompany.myappname) because this is already unique.
SKU stands for Stock-keeping Unit. It's more for inventory tracking purpose https://en.wikipedia.org/wiki/Stock_keeping_unit
The purpose of having a SKU is so that you can tie the app sales to whatever internal SKU number that your accounting is using.
Might be answer is late but look at Simple Information of SKU (Stock keeping unit) number is, it's an unique tracking number (an arbitrary number) that are used in appStore for your application. You can put whatever you want in there as long as it is unique among your applications. Try to follow a pattern for the SKU Number of your apps so that you will be able to better organize them. I suggest a combination of the current year + month + ID for your app. So if you’re developing your first application on september 1991 (oh,, yah it's my b'day's month and year :D ), you could put your SKU Number as “19910901”. Here, I am just suggesting you for this pattern but you can take/choose any pattern which easy for you.
As others have noted, "SKU" stands for stock keeping unit. Here's what I find currently (3 February 2017) in the Apple documentation regarding the "SKU Number:"
SKU Number
A unique ID for your app in the Apple system that is not seen by users. You can use letters, numbers, hyphens, periods, and underscores. The SKU can’t
start with a hyphen, period, or underscore. Use a value that is meaningful to your organization. Can’t be edited after saving the iTunes Connect record.
(internet archive link:) iTunes Connect Properties
I put the year and the number series of my app example 2014-01
The SKU example used in the documentation was to provide the allowed characters in a new user-specified SKU.
来源：https://stackoverflow.com/questions/8710512/itunes-connect-how-to-choose-a-good-sku