With the growing demand for cross-domain interoperability, it is necessary to discuss how DDI-Cross Domain Integration (DDI-CDI) interacts with a wider ecosystem of standards, each of which performs important functions that complement and are complemented by those that DDI-CDI brings to the table. In an increasingly interdisciplinary world, a single standard cannot cover all aspects of data interoperability, making it necessary to combine multiple standards for cross-domain data integration. We need to understand how standards interact, and this document is an attempt to provide a working description of this, from a DDI-CDI perspective. DDI-CDI provides the basic descriptive capability to enable interoperability of data and semantics across domains and the integration of heterogeneous datasets. In order to do this, it needs to interact with existing domain standards and those describing semantics. Therefore, we present below the case for why additional standards can and should be used with DDI-CDI.