The Import Mapping Template Wizard looks for the source and target definitions in the following location:

<PowerCenterInstallationDir>\client\MappingTemplate\tabledefs

You can export source and target definitions to this folder in the following ways:

The Import Mapping Template Wizard prompts you to export source or target definitions that are specified in parameters to the default location. If a source or target definition exists in the table definition location and you do not want to overwrite the current exported version, you can choose not to export the source or target definition. When you export the table definitions, ensure that you save the definitions in the correct location.