The Hierarchy Processor transformation can process information from different data sets. Some of the field names might not be unique among the different data sets. As a result, you can't simply reference the field by its name, because the same field name might be used in a different data set, or within the hierarchy of the same data set.

The syntax of the expressions in the Hierarchy Processor transformation differs from that used in the Expression transformation.

To reference a field in a Hierarchy Processor transformation, use the following syntax:

:fld.{input_group_name.field_name}.field_name

The following table describes the syntax in more detail:

Syntax part	Description
.fld.	Denotes the Hierarchy Processor transformation expression syntax.
input_group_name	Name of the input group or dataset.
field_name	Name of the field, including the full path name if it's not a top-level field. If any field is of the type array, include the array name. If an array is primitive and has no array name, use elem as the array name. For fields within a struct or an array, the actual field name is specified outside of the closing brace.
.field_name	Include the field_name portion only when referencing a field within a struct or an array. Follow these guidelines: For fields within a struct, the field_name portion uses the format: .structName.fieldname For fields within an array, the field_name portion uses the format: .fieldName