Content-related terminology

Input class

An ECClass of ECInstance we requested content for.

Input instance

An ECInstance we requested content for.

Primary instance

ECInstance whose properties are loaded at the root level of the content record.

This usually but not necessarily matches input instance — it depends on the content specifications that produce content:

  • Selected node instances specification returns content records whose input instance matches primary instance.
  • Content related instances specification returns content records whose input instance doesn't match primary instance. Instead, the primary instance is related to the input instance through a relationship defined in the specification.
  • Content instances of specific classes specification returns content records that don't rely on input instances at all.

Content records may also contain properties of related instances.

Primary class

An ECClass of the primary instance.

ECInstance that is related to primary instance.

Properties that belong to a related instance rather than primary instance.

Property merging

When content is requested for multiple different classes and they all have similar properties, multiple properties may get merged under one field.


Requesting content for Window and Door classes which both have property Height - content will contain only one field with name Height and values of both Window and Door instances will be put under that field.

Properties are considered similar if:

  • Names are equal
  • Types are equal
  • Renderers are equal
  • Editors are equal
  • For related properties only: related to the same property

Value merging

When content is requested with ContentFlags.MergeResults flag and contains more than 1 result row, its values are merged into 1 record. This is generally used only for property pane use case where we may request content for multiple selected elements.

Example of merged values:

Row Field 1 Field 2 Field 1
row 1 has value has value -
row 2 has value - has value
Result has value ***Varies*** ***Varies***

The above example would render into a similar property grid:

Field Value
Field 1 has value
Field 2 ***Varies***
Field 3 ***Varies***

Nested content

In most cases property values are primitive, arrays or structs. However, it is possible to set up related properties using one-to-many or many-to-many relationship which creates, what we call, the nested content.


          /  |  \
         /   |   \
        /    |    \
Element1 Element2 Element3

In the above example Model has 3 related Element instances. We can request content for Model and ask to additionally show related Element properties. In this case element properties are called nested content because properties of multiple Element instances are displayed as a single Model property. The property is created as an array of structs where each struct is created from Element instance.

Last Updated: 15 May, 2024