A set is a flexible structure for depicting hierarchies and quantities.
The set ID is only unique when used in combination with the table name.
Set IDs can contain letters, numbers as well as the special characters '_' (underscore) and '-' (hyphen). Please note the following:
Sets whose name begins with a number are delivered with the system or are created by special applications. In general set maintenance, you cannot create them, you can only display, change or delete them. If the first number is 0, you can only display the set.
Groups created in CO are technically stored as sets. However, they cannot be displayed or changed in general set maintenance. Nevertheless, you can still use groups in single or multi sets or in Report Writer reports.