If you need to filter your data to only send valid data to your output flows, you can create validation rules that will check your data. These validation rules can be a basic check for correct values or referential integrity check. For more information on how to create those rules, see Centralizing a Validation Rule in Managing Metadata. As they are stored at the metadata level in the Repository, they can be easily reused and modified.
To see how to use a validation rule, see the below section.