Difference between Customer Include and Append

Hi all,

We are using a special customer namespace /XXX/. Regarding to this I can not use the Customer Includes (CI_Include) in the SAP tables anymore to add own fields.

To create my own fields anyway I create a append in the /XXX/ namespace and add my /XXX/fields to this Append.

It is working, but I want to know if there are situations where the use of an append instead of an include can cause errors?

What is the difference between include and append?

Thanks in advance for your help,

Fabian