If you have multiple instances of a custom transformer in your workspace, editing one will cause changes in the others.

• A. True
• B. False
• C. Sometimes
• D. Only if they share the same parameters.

Answer: (A)

In FME, a Custom Transformer is a single reusable definition. When you place multiple instances of that same Custom Transformer in your workspace, each instance refers to that shared definition rather than having its own separate copy. Therefore, editing the internal structure or ports of the Custom Transformer updates the shared definition, and every instance automatically reflects those changes. This shared-definition behavior is what makes custom transformers powerful for consistent reuse. If you need different behavior for a particular spot, you’d create a local copy or clone of the Custom Transformer, or override parameters at the instance level, but the underlying definition remains shared.