Hi Donna, welcome to the OpenCDISC community.
The Validator does support extending CDISC Controlled Terminology in cases where the codelist is extensible. To make this work, you’ll need to provide it with a define.xml document that contains your custom codelists. Then, during validation, the Validator will use your codelists in place of the CDISC extensible codelists, where appropriate.
If you don’t happen to have a define.xml file for the data that you’re trying to validate, the OpenCDISC Validator provides a utility to create one that’s created from your data and our configuration documents. You can access this utility by selecting the “Generate define.xml” radio button in the desktop client. In order to add your codelists to the generated define.xml document, you’ll need to use the Excel template in the config/examples folder and specify it in the Code Lists field.
Regards,
Tim