Organization

The organizational model describes how the system’s content and functionality are ordered and categorized. It made up of the command structure and content structure of the application

Command Structure

A command is any function performed by the application based on user input. Commands that perform similar functions may be grouped together. The collection of commands and command groups make up the command structure of the application. The command structure of KDE applications fall into three categories:

Simple - When there are relatively few globally applicable commands (~ less than 10) and command groups (~ less than 4). Use command patterns for a simple command structure. Plasmoids should use a simple command structure.
Complex - When there are several globally applicable commands and command groups and relatively few frequently used commands (~ less than 8). Use command patterns for a complex command structure.
Very complex - When there are many globally applicable commands and command groups and many frequently used commands. Use command patterns for a very complex command structure.

When designing an application, it may be unclear what the command structure should be.

Start by assuming a simple command structure and select an associated command pattern.
As the design evolves, if the selected pattern becomes inadequate for completing the primary tasks of the application, consider a pattern for a more complex command structure.

Content Structure

The content structure depends on how the underlying content of the application is organized. The content of KDE applications fall into 4 categories:

Flat - When the pieces of application content are not grouped. E.g. a playlist, a slideshow or a list of documents or contacts. Use navigation patterns for a flat content structure. Plasma may use a flat content structure.
2-deep - When all application content are grouped into top-level categories. E.g. picture albums, music albums, email folders or tags. Use navigation patterns for a 2-deep content structure . Plasmoids should use no more than a 2-deep content structure.
3 deep - When all application content are grouped into categories, which are themselves be grouped into top-level categories. Content structures this deep should generally be avoided where possible. E.g. a music or video library. Use navigation patterns for a 3-deep content structure.
n-deep - When content is infinitely groupable. Content structures this deep should be avoided since it is difficult for the user to maintain awareness of their location in content structure. Examples include file systems and archives. Use navigation patterns for a n-deep content structure.