The noise filter to the VLC unit then outputs the filter data.

The VCL-RTL contains low-level classes and routines available for all VCL applications.

However, most of the documentation refers to the VCL-RTL as simply VCL.

The separation between the RTL and the VCL in RAD Studio is that the RTL is implemented in the System unit scope, whereas the VCL is implemented in the Vcl unit scope.

Use the VCL when you want to use native Windows controls, Windows-specific features, or extend an existing VCL application.

Major components of the Visual Component Library (VCL)

The Customer will notify us of any defects without delay.

FastReport VCL – a new generation of reporting tools.

Because VCL is mostly a thin wrapper on the Windows API, VCL based applications are much smaller than FireMonkey applications.

The VCL supports only the Windows target platform.

Because VCL has been around a while, you may have some existing VCL code that you want to integrate into your application.

Creates an application that can contain VCL components.

See also the syntax for forward declarations of VCL classes.

Custom groups (FireMonkey, RTL, <yourProject>, and so forth)

If you know VCL, development with FMX is relatively natural.