Use the following rules and guidelines when you create a Custom transformation:
Custom transformations are connected transformations. You cannot reference a Custom transformation in an expression.
You can include multiple procedures in one module. For example, you can include an XML writer procedure and an XML parser procedure in the same module.
You can bind one shared library or DLL to multiple Custom transformation instances if you write the procedure code to handle multiple Custom transformation instances.
When you write the procedure code, you must make sure it does not violate basic mapping rules.
The Custom transformation sends and receives high precision decimals as high precision decimals.
Use multi-threaded code in Custom transformation procedures.