ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Desktop.Editing Namespace / ParallelOffset Class / Selection Property

Selection Property (ParallelOffset)
Gets the lines to be copied from.
Syntax
public SelectionSet Selection {get;}
Remarks
If no line features are in the selection, the copy will fail.
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.2 or higher.
See Also