'Declaration
 
Public Sub SetFileExtension( _
   ByVal projectType As LlProject, _
   ByVal fileType As LlFileType, _
   ByVal extension As String _
) 

public void SetFileExtension( 
   LlProject projectType,
   LlFileType fileType,
   string extension
)

public:
void SetFileExtension( 
   LlProject projectType,
   LlFileType fileType,
   String^ extension
) 

Parameters

projectType

Project type (List, Label or Card) the file extension is to be queried for.

fileType

Type of the project file.

extension

File extension (without point).

The file extension to be set must be unique within the project types. Otherwise the LL_FileExists_Exception will be thrown.

Below the file extensions for list projects are changed.

...
LL.FileExtensions.SetFileExtension(LlProject.List, LlFileType.Project, "rpt");
LL.FileExtensions.SetFileExtension(LlProject.List, LlFileType.PrinterSettings, "rpp");
LL.FileExtensions.SetFileExtension(LlProject.List, LlFileType.Sketch, "rpv");
...

Platforms: Windows 10 (Version 21H2 - 22H2), Windows 11 (22H2 - 25H2), Windows Server 2016 - 2025
.NET: .NET Framework 4.8, .NET 8, .NET 9, .NET 10

Reference

FileExtensions Class
FileExtensions Members