The design of the ordered reference set supports two overall purposes:

1. Specifying a sequential order of a subset of components
2. Specifying prioritized groups within a subset of components 

Ordering

Ordered component reference set can be used to create a simple ordered list of components, i.e. a list that do not include any nesting, or groups. It can for example be used to prioritize the sort order of the descriptions with identical terms when they are displayed. It can also be used to specify the order of descriptions displayed in a simple pick list. 

Figure 5.3-1: Ordered reference set with no groups

Prioritization

Prioritization is similar to order but multiple components may have the same rank. In this case the value of the order attribute specify a priority order for a group of components. 

Figure 5.3-2: Ordered reference set with prioritized groups.

Reference Set Specific Attributes

Specific reference set attributes used to build an alternative hierarchical view of SNOMED CT