Which rules apply when creating subscreens in SAP?

When considering the creation of subscreens in SAP, the option stating that subscreens cannot have a field of type OK is correct because subscreens are designed to be part of a larger screen layout, typically to display or gather input for a specific context without requiring a separate logical unit for confirmation. Fields of type OK are generally used for primary screens where a user interface plays a significant role in user interaction, usually indicating an acceptance or continuation action within a stand-alone context.

In subscreens, which are subordinate to the main screen, the purpose is to provide additional details or functionality without having a self-sufficient user confirmation element like an OK button. By refraining from including fields of type OK, the design maintains clarity and prevents confusion in terms of how user interactions are processed within the larger application structure. This ensures that the focus remains on actions relevant to the parent screen's context rather than leading users to expect independent navigation.

The other options do not accurately reflect the restrictions or guidelines related to subscreens in SAP. For example, subscreens can indeed call other subscreens to create a tree of information that is organized hierarchically, which helps segment data entry or display. Additionally, subscreens can contain AT EXIT-COMMAND modules, which allow for processing