CustomSymbolDefinition is the base class that is used to create a support symbol (part) in .NET. To create a new symbol, the class that you use must inherit CustomSymbolDefinition. In this class, you should define CacheOption, SymbolVersion, and VariableOutputs.
To create symbols in Microsoft Visual Basic, implement IJDUserSymbolServices.
// A symbol can be Cached, Non-Cached or of Automatic Type.
[CacheOption(CacheOptionType.NonCached)]
// A symbol can have SymbolVersion and it can be specified as shown below.
[SymbolVersion("1.0.0.0")]
// A symbol can have variable inputs and outputs i.e. its functionality can
// be changed in future. So this can be specified by the attribute VaribleOutputs
[VariableOutputs]
public class WBAParts : CustomSymbolDefinition
{
// Declare inputs
// Definitions of Aspects and their Outputs
// Implement ConstructOutputs() to create the geometry and ports of symbol
}