There are different ways to use your own programming code in a report template:
With an external custom assembly:
With custom assemblies, you reference external code. Custom assemblies are useful if you want to maintain code in a single place and use it in multiple report templates. Custom assemblies must be .NET supported. The code may be written in C# or VB.NET.
With embedded custom code:
Custom code is defined in one specific report template and can be used only there. It cannot be shared across multiple report templates. Custom code must be written in Visual Basic.