The task itself should be focused on just completing that specific activity and nothing else. To help ensure that effect took keeping a general design rule of no more than five steps within a task definition. There will always be exceptions, and a task itself could run a traditional business process. However, in general, the maximum five-step rule helps you design the correct types of tasks. 

Note:  This design approach enables for tasks to be truly focused on specific business activities and the relationships between the activities. This can also enable task reuse. If a specific business activity is part of a larger task, that specific task cannot be used within the case lifecycle as needed without running the entire defined process. 

## Case interaction 

As shown in Figure 18-2 on page 560, there are several external entities that the case interacts with. The intent in this section is to outline those types of interactions. These interactions are all system-based, because the user interactions are covered from a task perspective and user interface (UI) perspective. 

The following list includes some of the entities where interactions are required: 

GLYPH<SM590000> Calendaring 

GLYPH<SM590000> Electronic medical records (EMR) 

GLYPH<SM590000> Billing 

GLYPH<SM590000> Documentation 

GLYPH<SM590000> Labs and tests 

GLYPH<SM590000> Procedures 

GLYPH<SM590000> Medication 

For each entity, a list of specific interactions must be created. This falls into a more technical type of design, and is covered in more detail in 18.4, “High-level design” on page 580. 

The next aspect of interactions to be determined is at the role level, which ties people into the identified entities and activities. These are the basic roles that we have defined: 

GLYPH<SM590000> Doctor 

GLYPH<SM590000> Nurse (at this point, it is unknown if the Nurse role must be broken down into more specific roles) 

GLYPH<SM590000> Medical Staff (at this point in the design, it is unknown if this role must be broken down into more specific roles) 

GLYPH<SM590000> Clerical Staff 

